Bradford VTS · Clinical Skills
Clinical Investigations
Order tests that answer a question — not tests that ask one.
Clinical investigations are one of the most over-used — and under-thought — tools in medicine. In GP, the art is not ordering every test under the sun; it is ordering the right test, at the right time, for the right reason. This page will teach you exactly how to think like a GP when it comes to investigations — and how to explain results clearly to patients in the SCA.
Section 1
📥 Downloads
Handouts, reference sheets, and teaching extras — ready when you are.
path: CLINICAL INVESTIGATIONS
Section 2
🌐 Web Resources
A hand-picked mix of official guidance and real-world GP training resources. Because sometimes the best pearls are not hiding in the official documents.
Core Clinical Guidance
ECG & Cardiology
Spirometry & Respiratory
Training & Exam Resources
Section 3
⚡ Quick Summary
Short on time? Read this first. Everything else is the explanation.
If You Read Only One Thing — Read This
Section 4
🧠 The GP Philosophy of Investigations
Before asking which test — ask why you are testing at all.
The Art of Focused Testing
The art of GP medicine is not ordering every test under the sun and working out what the diagnosis is afterwards. Anyone can do that — and it would break the NHS in the process.
The AKT and SCA test whether you are requesting focused, purposeful investigations or whether you are just doing a scattergun screen. The latter is not good doctoring.
⚠️ The False Positive Problem
In primary care, the prior probability of serious disease is low. This means that a positive result on a test is more likely to be a false positive than in a hospital setting.
Order tests without a clear clinical reason → generate anxiety → create harmful diagnostic cascades. Over-testing is a patient safety issue, not just a resource one.
Ask These 5 Questions Before Every Investigation
- 1What question am I trying to answer?
Be specific. "To rule out anaemia" is better than "routine bloods." "To confirm hypothyroidism in a patient with weight gain, fatigue, and bradycardia" is excellent.
- 2How will the result change my management?
If you will do the same thing regardless of the result, the test is not useful. If you genuinely need the answer to decide what to do next — it is worthwhile.
- 3Is the pre-test probability reasonable?
Ordering a D-dimer in a 25-year-old with a minor calf ache after a long flight? Reasonable. Ordering it in every patient with leg pain? Recipe for false positives and harm.
- 4Who will review the result, and when?
A test without a clear follow-up plan is dangerous. Document who is responsible. Make sure the patient knows how to get the result.
- 5Have I explained the test and its purpose to the patient?
Patients who understand why you are testing are less anxious while waiting for results — and more likely to act on abnormal findings.
Many trainees fail SCA stations on investigations not because they ordered the wrong test — but because they never explained to the patient why they were ordering it, what to expect, or how they would get the result back. Examiners notice. Say it out loud.
🏆 The Golden Rules of GP Investigations
The 6 Golden Rules
- Purpose-driven testing — every test must answer a specific clinical question
- Pre-test probability thinking — don't test low-risk patients; testing creates harm when probability is low
- Minimal effective set — the smallest number of genuinely useful tests
- Patient-centred explanation — explain WHY you are ordering, not just WHAT you are ordering
- Plan the results pathway — what happens if normal? If abnormal? If borderline?
- Safety-net always — results do not replace clinical vigilance
⚠️ The Trainee Fail Patterns (Very High Yield)
Never say or do:
- "Routine bloods" / "full panel just in case"
- "Let's just do some tests and see"
- Ordering without explaining the purpose to the patient
- No follow-up plan mentioned for results
- Assuming normal result = no risk
- Ordering ≥4 tests without clear reasoning for each
You are judged more on reasoning than knowledge. Fewer tests + clear reasoning = higher score. Saying your thinking out loud is essential. Over-investigation is seen as unsafe, not safe.
🧭 The 6-Step Practical Decision Framework
Think through these six steps every time you reach for an investigation.
- 1What serious thing must I not miss?
Cancer, sepsis, AKI, cauda equina, ACS, ectopic pregnancy, testicular torsion, giant cell arteritis, acute glaucoma. Your test choice should address these first.
- 2What is the most likely diagnosis?
Your first-line test should be tied to the most probable story. Test for what is most likely AND most dangerous — not everything possible.
- 3Which test will genuinely change management?
If the answer is "none — I'd do the same regardless," do not order the test. This single filter eliminates most defensive testing.
- 4What is the BEST first test — not the fanciest?
X-ray before CT in chest/bone questions. USS before CT in biliary/pelvic/renal. No imaging at all in most routine low back pain without red flags (NICE-aligned). Cheaper, faster, lower risk is often the correct AKT answer.
- 5Explain the why, the what, and the what-next to the patient
This is what converts safe medicine into a high-scoring SCA consultation. Patients who understand the purpose of their test are less anxious and more likely to engage with follow-up.
- 6Own the result pathway
A GP who orders a test is responsible for reviewing it, acting on it, communicating what matters, and documenting the follow-up. "The system will catch it" is not a plan — and is a common source of clinical negligence claims in primary care.
If the answer is no → don't order. This filter eliminates most defensive testing.
If you cannot explain the purpose of a test in 10 seconds, reconsider whether you have a strong enough reason to order it.
Section 22 — Imaging in Primary Care
🖼️ Which Investigation For Which Job? Imaging Guide
Choosing the right imaging is as important as choosing the right blood test. A CXR when you need an MRI is wasted time. An MRI when you need a CT is delayed diagnosis. This section tells you which tool to reach for — and why.
🩻 X-Ray (Plain Radiograph)
Good for:
- Fractures and bony injury
- Chest: pneumonia, pneumothorax, pleural effusion, heart failure, COPD (hyperinflation), lung mass
- Bowel: obstruction (erect AXR), free gas under diaphragm (perforation)
- Joints: osteoarthritis changes, joint space narrowing, calcification
- Foreign bodies
- First-line investigation for most musculoskeletal and chest presentations
A GP-initiated CXR has a false-negative rate of approximately 17–20% for lung cancer (Leeds BJGP study: 17.7%; UK systematic review: "at least 20%"). Tumours hidden behind the hilum, heart, ribs, or clavicle are frequently missed. A normal CXR in a symptomatic patient at risk does not rule out lung cancer — if clinical suspicion remains, escalate to CT chest. Never be falsely reassured by a negative CXR.
📌 Radiation context: a single CXR delivers ~0.02 mSv — roughly equivalent to 2 cigarettes worth of radiation risk, or about 3 days of normal background radiation. This is one of the lowest-dose radiological investigations.
Not good for:
- Soft tissue detail (tendons, ligaments, cartilage, muscles)
- Brain pathology (use CT or MRI)
- Abdominal organ detail (use USS or CT)
- Early infection / subtle fractures (may be normal)
- Spinal cord (use MRI)
🔊 Ultrasound (USS)
Good for:
- Abdominal organs: liver (fatty liver, cirrhosis, lesions), gallbladder (stones), kidneys (hydronephrosis, cysts), spleen, bladder
- Pelvic organs: uterus, ovaries (cysts, fibroids), early pregnancy, ectopic
- Thyroid and neck (nodules, lymph nodes)
- Testes (torsion, epididymitis, mass — urgent)
- Deep vein thrombosis (limb Doppler)
- Superficial soft tissue (lipoma, abscess, hernia)
- Guided procedures (joint aspiration, biopsy)
- Cardiac: ECHO for structure and function
Not good for:
- Bowel (gas causes artefact)
- Lungs (air is opaque to sound)
- Brain in adults (skull blocks sound)
- Bone detail
🧊 CT (Computed Tomography)
Good for:
- Emergency: head injury, acute stroke (bleed), PE (CT-PA), AAA, trauma, bowel perforation
- Chest: lung cancer staging, HRCT for interstitial lung disease (ILD), CT-PA for PE
- Abdomen/pelvis: cancer staging, diverticulitis, bowel obstruction, pancreatitis
- Bony detail: complex fractures, vertebral fractures, sinuses, temporal bone
- Rapid assessment — much faster than MRI in emergency
- CT colonography (virtual colonoscopy) for colorectal cancer screening in some patients
Not good for:
- Spinal cord and nerve root detail (MRI better)
- Soft tissue joint detail (MRI better)
- Early ischaemic stroke (<24h — MRI diffusion weighted is better)
- Liver lesion characterisation (MRI better)
- Prostate and endometriosis staging (MRI better)
🧲 MRI (Magnetic Resonance Imaging)
Good for:
- Brain: tumours, MS plaques, epilepsy workup, posterior fossa, early stroke (DWI)
- Spine: disc prolapse, cord compression, spinal stenosis, cauda equina — gold standard
- Soft tissue joints: knee (menisci, ligaments), shoulder (rotator cuff), hip (labrum), wrist
- Liver lesion characterisation (MRI with contrast)
- Prostate cancer staging (multiparametric MRI — mpMRI) — now first line
- Pelvis: endometriosis staging, rectal cancer staging
- Cardiac MRI: cardiomyopathy, myocarditis, viability assessment
- MRCP: biliary and pancreatic ducts (alternative to ERCP for diagnostic use)
Not good for / limitations:
- Emergency setting (slow, 30–60 min, patient must be still)
- Claustrophobia (may need open MRI or sedation)
- Acute fractures — CT better for bony cortex detail
- Pacemakers, certain metal implants (absolute contraindication — check MHRA guidance)
- First trimester pregnancy — avoid in first 12 weeks unless essential
Emergency / bone / fast assessment → CT. Soft tissue / brain detail / spine / prostate / no radiation → MRI. CT is quicker, more available, and better for bone and emergency. MRI is superior for most soft tissue and neurological detail and uses no radiation. When in doubt in primary care: discuss with radiology before requesting — they would rather help you choose than receive an inappropriate request.
🔶 Think CT first when:
"Bones, Stones, Blood, Lungs, Organs"
Fractures • Renal stones • Acute haemorrhage • PE / lung cancer • Abdominal emergencies
🔷 Think MRI first when:
"Joints, Nerves, Brain, Cord, Soft tissue"
Ligaments/menisci • Neuropathy • Tumours • SACD • Disc prolapse
Imaging by Body System — Quick Reference
| System / Presentation | First-Line | Second-Line / Specialist | GP Notes |
|---|---|---|---|
| Joints (acute injury) | X-ray (fracture, OA) | MRI (soft tissue: ligaments, menisci, rotator cuff, labrum) | USS good for joint effusions and guided injections. MRI is gold standard for sports injuries and pre-surgery planning. |
| Joints (inflammatory) | X-ray (erosions, joint space loss in RA) | USS (synovitis, power Doppler in early RA), MRI for sacroiliac joints (axial spondyloarthropathy) | Early RA: X-ray often normal. USS more sensitive for synovitis. MRI sacroiliac joints for suspected ankylosing spondylitis. |
| Lungs / respiratory | CXR (pneumonia, effusion, pneumothorax, mass) | CT chest (HRCT for ILD, CT-PA for PE, staging lung cancer); spirometry for function | CT-PA is the investigation of choice for suspected PE. HRCT is essential for diagnosing ILD. CT chest for any suspicious CXR finding. |
| Brain (emergency) | CT head (acute bleed, fracture, herniation) | MRI brain (tumour, MS, epilepsy, posterior fossa pathology, early ischaemic stroke) | CT in A&E for acute presentation. MRI for most elective neurological workup. CT may miss early ischaemic stroke and posterior fossa lesions. |
| Abdomen / gastro | USS (liver, GB, kidneys, spleen, pancreas head) | CT abdomen/pelvis (staging, obstruction, diverticulitis, pancreatitis); endoscopy (upper and lower GI); MRI liver / MRCP | USS is first line for most abdominal pain with systemic features. CT for suspected cancer, obstruction, acute abdomen. MRCP for biliary pathology without invasive ERCP. |
| Heart | ECG, CXR | Echocardiography (structure + function — valve disease, LVH, cardiomyopathy, pericardial effusion); CT coronary angiography (CAD risk stratification); cardiac MRI (cardiomyopathy, myocarditis) | Refer for echo if: new AF, suspected heart failure, murmur, breathlessness without clear cause. Cardiac MRI for complex cardiomyopathy and myocarditis. |
| Skin lesions | Clinical examination + dermoscopy | Biopsy / histology (definitive); USS for depth of lesion | Imaging rarely the primary investigation for skin. Refer suspected melanoma via 2-week wait pathway for clinical assessment and excision biopsy. USS for lipoma or abscess characterisation. |
| Urinary tract | Urine dipstick + MSU; USS kidneys/bladder | CT KUB (renal/ureteric stones — gold standard); CT urogram (haematuria pathway — NICE NG12); cystoscopy | Visible haematuria without UTI → urgent 2WW referral (urology). CT KUB replaces plain KUB for stones — far more sensitive. USS for kidneys if obstructed, cysts, hydronephrosis. |
| Sexual / reproductive | USS pelvis (uterus, ovaries, testes) | MRI prostate (mpMRI — now first-line before biopsy in suspected prostate cancer); MRI pelvis for endometriosis staging, rectal cancer; transvaginal USS (TVS) for endometrial thickness | Scrotal USS urgent for suspected testicular torsion or tumour. mpMRI prostate before any biopsy. TVS is gold standard for endometrial abnormality. |
| Eyes | Clinical examination, fundoscopy, visual acuity, slit lamp (optometrist/ophthalmologist) | OCT (optical coherence tomography) for retinal detail — AMD, glaucoma; USS for vitreous/retinal detachment; CT/MRI orbit for mass or trauma | Most eye investigations are performed in specialist settings. In GP: refer urgently for visual loss, painful red eye, flashing lights/floaters (detachment), diplopia. |
| ENT | Clinical examination, nasoendoscopy (ENT) | CT sinuses (chronic sinusitis, pre-op); CT temporal bone (cholesteatoma, glomus tumour); MRI neck (soft tissue mass, acoustic neuroma — CPA lesion); USS neck (thyroid, lymph nodes) | Unilateral sensorineural hearing loss → urgent MRI to exclude acoustic neuroma. Neck lump persistent >3 weeks → 2WW USS + consider fine needle aspiration. |
| Neuro (elective) | MRI brain (gold standard for most elective neuro) | CT brain (emergency/acute), nerve conduction studies + EMG (peripheral nerve and muscle), EEG (epilepsy) | MRI is gold standard for most neurological workup. Nerve conduction for neuropathy, carpal tunnel, motor neurone disease. EEG for seizure type classification. |
| Spine | X-ray spine (fracture, alignment, degeneration, spondylolisthesis) | MRI spine (gold standard for disc prolapse, cord compression, cauda equina, spinal stenosis, myelopathy); CT spine (complex fractures, pre-surgical) | Cauda equina syndrome = emergency MRI. Any progressive neurological deficit = urgent MRI. Routine back pain with no red flags: do NOT image in first 6 weeks. X-ray if >50, trauma, or red flags. |
| Spine — radicular pain (sciatica) | No imaging initially for simple sciatica without red flags | MRI spine if red flags present or progressive/severe neurological deficit. CT myelogram if MRI contraindicated. | AKT trap: routinely imaging simple sciatica. Most resolves within 6–12 weeks with conservative management. Red flags (cauda equina, progressive motor deficit) = emergency MRI same day. |
| Fractures | X-ray | CT if: complex fracture (e.g. tibial plateau, calcaneum, pelvis), normal X-ray but high clinical suspicion (e.g. suspected scaphoid, neck of femur). MRI for stress fractures, bone marrow oedema. | Scaphoid fracture: X-ray may be negative in first 10 days — if suspected, immobilise and repeat X-ray or MRI at 7–10 days. A missed scaphoid fracture = avascular necrosis risk. |
| GI — gallstones / biliary | USS abdomen (biliary system) | MRCP (non-invasive — preferred diagnostic test for bile duct stones, biliary stricture); CT if complications (empyema, abscess, pancreatitis); ERCP if therapeutic intervention needed | USS for gallstones: sensitive. Less good for common bile duct. If obstructive pattern (raised ALP/GGT + bilirubin) → MRCP or CT in secondary care. Refer if: jaundice, pancreatitis, suspected choledocholithiasis. |
| GI — suspected appendicitis (adult) | Surgical admission for clinical assessment; USS (especially in young women / pregnant — avoid radiation) | CT abdomen/pelvis (more sensitive, especially in equivocal adult cases); MRI preferred in pregnancy to avoid radiation | In primary care: refer direct to surgical assessment without delay. Do not arrange imaging from GP — this delays treatment. USS is first imaging of choice in young women/pregnancy to avoid radiation. |
| GI — suspected IBD | Faecal calprotectin, FBC, CRP, coeliac screen → colonoscopy via secondary care | CT or MR enterography for small bowel Crohn's disease; USS abdomen for disease activity monitoring | Faecal calprotectin <50 µg/g makes IBD unlikely. If raised and IBD suspected → refer for colonoscopy. MR enterography is gold standard for small bowel Crohn's (no radiation; better soft tissue). |
| Heart failure | NT-proBNP (or BNP) → echocardiogram if raised; ECG, CXR, FBC, U&E, TFTs | Cardiac MRI: detailed structure/function in specialist care (cardiomyopathy characterisation, myocarditis, viability). CT coronary angiography for suspected concomitant CAD. | AKT trap: ordering echo without NT-proBNP first. NICE: check NT-proBNP first. NT-proBNP <125 pg/mL (or BNP <35 pg/mL) = heart failure unlikely. If >400 pg/mL → urgent echo (≤2 weeks). Also check TFTs — hypothyroidism causes reversible heart failure. |
| Prostate (LUTS / suspected cancer) | PSA + DRE (+ age-related PSA reference range) | Multiparametric MRI prostate (mpMRI) via urology — NICE: now first-line before any biopsy in suspected prostate cancer | AKT trap: going straight to TRUS biopsy without mpMRI. NICE NG131: mpMRI should precede biopsy. PSA alone is not diagnostic — combine with clinical suspicion. Refer via 2WW if PSA raised or DRE abnormal. |
| Sexual health (STIs) | NAAT swabs (cervical / urethral / throat / rectal), first-void urine; blood tests: HIV, syphilis (TPHA/RPR), hepatitis B (HBsAg), hepatitis C (HCV Ab) | Pelvic USS only if PID complications suspected (tubo-ovarian abscess, pyosalpinx). CT/MRI pelvis for complex pelvic sepsis. | Imaging is NOT a routine part of STI testing in primary care. Clinical diagnosis and swabs are first line. Pelvic USS only if severe PID or abscess suspected — these patients often need admission. |
Cauda equina features (bilateral leg weakness/numbness, saddle anaesthesia, bladder/bowel dysfunction) → emergency MRI same day. Suspected testicular torsion → emergency scrotal USS (or direct to urology — time critical). New focal neurology + headache + fever (meningitis/abscess) → CT head then LP, or direct A&E. Suspected ruptured AAA → direct to A&E, do not wait for imaging in the community.
In the UK, ionising radiation requests (X-ray, CT, nuclear medicine) are governed by the Ionising Radiation (Medical Exposure) Regulations (IRMER 2017). As the referrer, you must provide sufficient clinical justification. Writing "?pathology" on a CT request is not adequate justification. Be specific: "35-year-old with 3-week history of haemoptysis, smoker, CXR shows possible right hilar mass — CT chest for further characterisation and staging." This also improves the quality of the report you receive back.
Section 5
🩸 Interpreting COMMON Blood Tests in GP Land
The most common investigations you will order — and what they actually tell you.
Full Blood Count (FBC) — and what to do with it ▶
| Abnormality | What It Suggests in GP | Key Action |
|---|---|---|
| Low Hb (anaemia) | Iron deficiency (most common in GP), B12/folate, chronic disease, haemolysis, haematological malignancy | Check MCV, ferritin, B12/folate. Exclude GI cause in adults over 50. |
| Low MCV (microcytic) | Iron deficiency anaemia, thalassaemia, sideroblastic anaemia | Check ferritin (low = iron deficiency). Consider haemoglobin electrophoresis if suspected thalassaemia. |
| High MCV (macrocytic) | B12 or folate deficiency, hypothyroidism, alcohol excess, liver disease, drugs (methotrexate, hydroxyurea) | Check B12, folate, TFTs, LFTs. Ask about alcohol. |
| High WCC (leucocytosis) | Infection, inflammation, stress response, steroids, malignancy (CML) | Correlate with CRP/ESR. Repeat if incidental finding. |
| Low WCC (leucopenia) | Viral infection, bone marrow suppression (drugs, malignancy), B12/folate deficiency, autoimmune disease | Review medications. Consider haematology referral if persistent. |
| Low platelets (thrombocytopenia) | ITP, drugs (heparin, NSAIDs), liver disease, viral illness, B12/folate deficiency, malignancy | Check LFTs, B12/folate. Review medications carefully. |
| High platelets (thrombocytosis) | Reactive (infection, iron deficiency, post-splenectomy), essential thrombocythaemia (rare) | Identify underlying cause. Persistent isolated high platelets → haematology. |
Treating a low Hb with iron without finding out why. Always ask: why is this patient anaemic? In women of childbearing age, menorrhagia is common. In anyone over 50, exclude GI blood loss. Don't give iron and wave goodbye.
Urea & Electrolytes (U&E) / Renal Function ▶
| Result | Key GP Causes | Action |
|---|---|---|
| Raised creatinine / low eGFR | CKD (most common), acute kidney injury, dehydration, nephrotoxic drugs (NSAIDs, gentamicin) | Stage CKD. Check ACR. Review medications. Refer if eGFR <30 or deteriorating rapidly. |
| Hyperkalaemia (>5.5) | CKD, ACE inhibitors/ARBs, potassium-sparing diuretics, Addison's, haemolysed sample | First: check for haemolysis (pseudo-hyperkalaemia). If genuine: ECG, review medications, urgent action if >6.5. |
| Hypokalaemia (<3.5) | Loop/thiazide diuretics, vomiting, diarrhoea, eating disorders, laxative abuse, Conn's syndrome | Replace potassium. Find the cause. Monitor ECG if symptomatic or K+ <3.0. |
| Hyponatraemia (<135) | SIADH, hypothyroidism, Addison's, diuretics, heart/liver/renal failure, psychogenic polydipsia | Check serum osmolality, urine sodium/osmolality, TFTs, short Synacthen if Addison's suspected. |
| Hypernatraemia (>145) | Dehydration (commonest in GP), diabetes insipidus, excess sodium intake | Hydrate. Investigate if persistent or no clear cause. |
Haemolysed sample is the most common cause of a mildly elevated K+ (5.1–5.5) in an otherwise well patient. Always repeat before acting. But never delay an ECG if the patient is symptomatic or the K+ is above 6.0.
Liver Function Tests (LFTs) ▶
| Pattern | Raised enzymes | Likely Cause |
|---|---|---|
| Hepatocellular injury | ALT & AST ↑↑ (more than ALP) | Alcohol, viral hepatitis, NAFLD, drugs (statins, methotrexate), autoimmune hepatitis |
| Cholestatic pattern | ALP & GGT ↑↑ (more than ALT) | Gallstones, primary biliary cholangitis, drugs, pregnancy |
| Mixed pattern | All raised together | Can occur in many conditions. Consider GGT ratio to distinguish liver from bone source of ALP. |
| Low albumin | Albumin ↓ | Chronic liver disease, malnutrition, nephrotic syndrome, sepsis, malignancy |
GGT is sensitive but not specific — it is raised by alcohol, many drugs, and even fatty liver. An isolated raised GGT is a common GP problem. Always ask about alcohol and medication use before ordering an expensive cascade of further tests.
Raised ALP is NOT always liver disease. Bone disease (Paget's, metastases, osteomalacia) also raises ALP without affecting GGT. If ALP is raised but GGT is normal, think bone before liver.
Thyroid Function Tests (TFTs) ▶
| TSH | Free T4 | Interpretation | GP Action |
|---|---|---|---|
| ↑ TSH | Low/normal fT4 | Hypothyroidism (overt or subclinical) | Start levothyroxine if overt. For subclinical: if TSH >10 or symptomatic, consider treating. |
| ↓ TSH | High fT4 | Hyperthyroidism | Refer/treat. Block-and-replace or carbimazole. Graves' disease most common cause. |
| ↓ TSH | Normal fT4 | Subclinical hyperthyroidism | Exclude T3 toxicosis. Monitor or refer depending on cause and degree. |
| Normal TSH | — | Euthyroid | Thyroid disease very unlikely. Don't repeat unless strong clinical reason. |
In SCA, be careful of the patient with "mildly raised TSH" who is already on levothyroxine. The question is often about dose adjustment, not new diagnosis. Check compliance and timing of dose before blood test before adjusting the dose.
Glucose & HbA1c — Diabetes Diagnosis ▶
| Test | Normal | Pre-diabetes (IGR) | Diabetes |
|---|---|---|---|
| HbA1c | <42 mmol/mol | 42–47 mmol/mol | ≥48 mmol/mol |
| Fasting plasma glucose | <6.1 mmol/L | 6.1–6.9 mmol/L | ≥7.0 mmol/L |
| Random plasma glucose | — | — | ≥11.1 mmol/L (with symptoms) |
| OGTT 2hr glucose | <7.8 mmol/L | 7.8–11.0 mmol/L | ≥11.1 mmol/L |
- In asymptomatic patients: two abnormal results are required for diagnosis
- In symptomatic patients: one abnormal result is sufficient
- HbA1c should not be used for diagnosis in: haemolytic anaemia, recent blood transfusion, haemoglobinopathy, pregnancy
- Use HbA1c ≥48 mmol/mol — the old percentage equivalent was ≥6.5%
Vitamin B12 & Folate ▶
Causes of B12 Deficiency
IRREVERSIBLE — usually need lifelong IM B12:
- Pernicious anaemia / autoimmune gastritis — intrinsic factor absent; oral absorption permanently impaired
- Post-gastrectomy / major gastric surgery — permanent loss of intrinsic factor production
- Terminal ileal disease or resection (e.g. Crohn's with ileal resection) — absorption sites lost
- Chronic atrophic gastritis with confirmed irreversible parietal cell loss
REVERSIBLE — may not need lifelong IM B12:
- Strict vegan / vegetarian diet — oral supplements usually sufficient if cause corrected
- Metformin use — impairs absorption; supplement orally or consider IM
- PPI long-term use — consider oral supplementation
- GI inflammation (e.g. active coeliac, Crohn's flare) — treat underlying condition
Local practice varies — check your area's shared care guidance.
Which Investigation to Use?
| Situation | Best Test |
|---|---|
| General screening / most adults | Total serum B12 (widely available) |
| Pregnancy / breastfeeding | Active B12 (holotranscobalamin) — total B12 falls physiologically in pregnancy |
| Suspected nitrous oxide deficiency | Plasma homocysteine or serum MMA — do NOT rely on total or active B12 (may be falsely normal) |
| Borderline B12 + persisting symptoms | MMA ± homocysteine — confirm functional deficiency even when B12 appears "normal" |
Nitrous oxide oxidises the cobalt core of cobalamin → functional deficiency where B12 cannot work even if serum levels look normal. MMA and homocysteine rise when B12-dependent metabolism fails — they detect the problem that serum B12 misses.
🎈 Nitrous Oxide (Laughing Gas) — A High-Yield GP Trap
Clinical features to watch for in young patients:
- Paraesthesia (especially hands and feet)
- Gait disturbance, ataxia, falls
- Weakness (spastic paraparesis)
- Psychiatric or cognitive symptoms
- Sensory level — suggests subacute combined degeneration (SACD)
Clinical approach:
- Ask specifically about "balloons", "whippits/whippets" or "laughing gas" — young patients rarely volunteer this
- Heavy recreational use (especially 16–24-year-olds) is strongly associated with myeloneuropathy
- Serum B12 and active B12 may be entirely normal — do not be falsely reassured
- Positive test: raised plasma homocysteine or serum MMA
- Neurological signs → parenteral B12 immediately + urgent neurology/acute medicine referral
Severe megaloblastic anaemia (dyspnoea, tachycardia, cardiac compromise) → start IM hydroxocobalamin loading urgently; refer to acute medicine / haematology.
SACD / suspected nitrous oxide myeloneuropathy (sensory ataxia, positive Romberg, spastic paraparesis, extensor plantars) → parenteral B12 immediately + urgent specialist input. In these situations: treat first, refine aetiology afterwards. The risk of neurological progression outweighs any risk of masking another diagnosis.
Without neurological involvement: 1 mg IM three times a week for 2 weeks → then 1 mg every 2–3 months for life (if irreversible cause).
With neurological involvement: 1 mg IM on alternate days until no further improvement → then 1 mg every 2 months for life. Seek specialist advice if uncertain.
Oral cyanocobalamin or hydroxocobalamin may be used for nutritional/dietary deficiency where intrinsic factor is intact — see NICE CKS / local formulary for dosing.
Lipids, Cardiovascular Risk, & CRP ▶
| Test | Key Threshold | GP Use | ||
|---|---|---|---|---|
| Total cholesterol | Optimal <5 mmol/L; treat if 10yr CV risk ≥10% (QRisk3) | Risk stratification; statin initiation | ||
| Non-HDL cholesterol | Primary target on statins (non-HDL <2.5 mmol/L) | Better predictor than LDL alone in treated patients | ||
| HDL cholesterol | M: >1.0 mmol/L; F: >1.2 mmol/L | Healthy lifestyle, aerobic exercise, moderate alcohol (not a clinical concern when high) | Metabolic syndrome, obesity, type 2 diabetes, physical inactivity, smoking, drugs (beta-blockers, anabolic steroids) | Low HDL increases cardiovascular risk even when total cholesterol is normal — do not be falsely reassured by a "normal" total cholesterol if HDL is low. Non-fasting lipid samples are generally acceptable for CV risk screening. Non-fasting triglycerides run ~20–30% higher than fasting. |
| Triglycerides | >10 mmol/L → pancreatitis risk | Lifestyle advice; fibrates if very high | ||
| CRP (C-reactive protein) | >10 mg/L = significant inflammation | Useful to distinguish infection from non-infectious inflammation; point-of-care CRP reduces antibiotic prescribing | ||
| ESR | Varies by age and sex | Useful for giant cell arteritis (ESR typically >50), myeloma screening, monitoring disease activity |
Use QRISK3 (not Framingham) for 10-year cardiovascular risk assessment. Offer high-intensity statins (atorvastatin 20mg) if QRISK3 ≥10%. Review lipids after 3 months of treatment targeting ≥40% reduction in non-HDL cholesterol.
Other Common Blood Tests in GP ▶
| Test | Key Facts for GP |
|---|---|
| Ferritin | Low ferritin = iron deficiency. Normal/high ferritin does not rule out functional iron deficiency in inflammation (ferritin is an acute phase protein). |
| Bone profile (Ca, PO4, ALP) | Hypercalcaemia in GP: primary hyperparathyroidism most common. Malignancy next. Check PTH. Hypercalcaemia + raised ALP but normal PTH → malignancy. |
| PSA | Raised PSA is not diagnostic of prostate cancer. Use alongside DRE and shared decision-making. Age-specific ranges apply. Recheck after 4–6 weeks if raised but no symptoms suggesting infection. |
| Coeliac antibodies (tTGA) | Must be on gluten-containing diet for result to be valid. Negative tTGA on gluten-free diet is meaningless — this is a classic trap. |
| D-dimer | Only useful if pre-test probability is LOW. Do not use if pre-test probability of VTE is high — go straight to imaging. False positives occur with infection, malignancy, pregnancy, surgery. |
| CA125 | For ovarian cancer risk assessment via NICE NG12. Not a diagnostic test alone. Use with pelvic ultrasound. |
| Short Synacthen Test (SST) | Tests adrenal function. Normal: cortisol rises to >500 nmol/L at 30 minutes. Insufficient rise = adrenal insufficiency. |
Section 23 — Master Blood Test Reference
🩸 Complete Reference Table for GP Bloods
Every common blood test you will encounter in GP: what it measures, the normal range, what causes it to be high or low, and the clinical mindfulness points you need to know. This is the reference you'll use for years.
Reference ranges vary between laboratories. Always use your local lab's reference range. The values shown here are standard adult ranges commonly used in UK NHS laboratories, provided for educational orientation only. Always interpret results in the context of the patient's age, sex, comorbidities, medications, and clinical presentation.
🔴 Full Blood Count (FBC)
| Test | What It Measures | Normal Range (Adult) | Causes of HIGH Result | Causes of LOW Result | ⚠️ Be Mindful Of |
|---|---|---|---|---|---|
| Haemoglobin (Hb) | Oxygen-carrying capacity of blood | M: 130–175 g/L F: 120–165 g/L | Polycythaemia vera, dehydration (relative), high altitude, COPD (secondary polycythaemia), testosterone use | Iron deficiency, B12/folate deficiency, chronic disease, haemolysis, haemorrhage, haematological malignancy, bone marrow failure, hypothyroidism, renal failure (↓EPO) | Hb <70 g/L — discuss urgently. In men, any anaemia needs cause found. In women of childbearing age, consider menorrhagia. Over-50s with low Hb → exclude GI malignancy. |
| MCV (Mean Cell Volume) | Average red cell size | 80–100 fL | Macrocytosis: B12/folate deficiency, alcohol, hypothyroidism, liver disease, drugs (methotrexate, hydroxyurea, azathioprine), reticulocytosis | Microcytosis: iron deficiency (commonest), thalassaemia, sideroblastic anaemia, anaemia of chronic disease (sometimes) | MCV can be normal even with combined deficiency (e.g., B12 + iron — they cancel each other out). Always check iron AND B12/folate together in unexplained anaemia. |
| WBC (White Blood Count) | Total white blood cell count — immune defence | 4.0–11.0 × 10⁹/L | Bacterial infection, inflammation, steroid use, stress response, CML (very high), smoking, post-splenectomy | Viral infection (especially early), bone marrow suppression (chemotherapy, drugs), B12/folate deficiency, aplastic anaemia, autoimmune (SLE), severe sepsis | Always look at differential (neutrophils, lymphocytes, eosinophils). Eosinophilia: consider allergy, parasitic infection, drugs, haematological. Lymphocytosis: CLL in older patients. |
| Neutrophils | Primary bacterial defence | 1.8–7.5 × 10⁹/L | Bacterial infection, steroids, acute MI, post-surgery, CML | Viral infection, drugs (clozapine — monitor mandatory), carbimazole, cytotoxics, B12/folate deficiency, racial neutropenia (benign in Afro-Caribbean individuals) | Neutropenia <1.0 × 10⁹/L = significant infection risk. Clozapine: absolute neutrophil count must be monitored — stop immediately if severely low. Benign ethnic neutropenia is common in Afro-Caribbean patients and does not require investigation. |
| Platelets | Blood clotting and haemostasis | 150–400 × 10⁹/L | Reactive: iron deficiency (most common in GP), infection, inflammation, post-splenectomy, post-surgery, IBD. Essential thrombocythaemia (primary — rare but important) | ITP (immune), drugs (heparin — HIT, NSAIDs, carbamazepine), bone marrow failure, B12/folate deficiency, liver disease (↓TPO), DIC, TTP, hypersplenism | High platelets + low MCV + low ferritin = iron deficiency thrombocytosis — treat the iron. Platelets consistently >600 × 10⁹/L need haematology review. Thrombocytopenia <50 before any procedure — discuss with haematology. HIT: platelet drop 5–10 days after heparin exposure — stop heparin immediately. |
🧪 Renal Function (U&E)
| Test | What It Measures | Normal Range | Causes of HIGH | Causes of LOW | ⚠️ Be Mindful Of |
|---|---|---|---|---|---|
| Sodium (Na⁺) | Osmolality and fluid balance regulation | 135–145 mmol/L | Dehydration (most common), diabetes insipidus, excess sodium intake | SIADH, hypothyroidism, Addison's disease, diuretics (thiazides especially), heart/liver/renal failure, psychogenic polydipsia | Na <125 or >155 = urgent management. Correcting hyponatraemia too fast causes osmotic demyelination syndrome (central pontine myelinolysis). Always measure serum osmolality and urine Na/osmolality to find the cause. |
| Potassium (K⁺) | Membrane potential, cardiac and muscle function | 3.5–5.5 mmol/L | CKD, ACE inhibitors/ARBs, K-sparing diuretics, Addison's, beta-blockers, haemolysis (spurious — very common!) | Loop/thiazide diuretics, vomiting, diarrhoea, eating disorders, laxative abuse, Conn's syndrome, insulin/beta-agonists (transient) | K⁺ >6.5 = emergency (ECG immediately). Most mildly raised K⁺ in primary care = haemolysed sample — repeat before acting. K⁺ <3.0 = risk of dangerous arrhythmias. "Triple whammy" (ACEi + diuretic + NSAID) → hyperkalaemia AND AKI risk. |
| Creatinine | Renal function (muscle breakdown product filtered by kidneys) | M: 60–110 µmol/L F: 45–90 µmol/L | CKD, AKI, dehydration, high muscle mass (bodybuilders — spurious), rhabdomyolysis | Low muscle mass (elderly, malnutrition, frailty) — eGFR may overestimate renal function in these patients | Creatinine does not rise until ~50% of renal function is already lost. In elderly patients with low muscle mass, creatinine may be "normal" despite significant CKD — always look at eGFR too. |
| eGFR | Estimated glomerular filtration rate — how well kidneys are filtering | >90 mL/min/1.73m² (normal); <60 = CKD if persistent ≥3 months | N/A (higher is better) | CKD, AKI, dehydration, nephrotoxic drugs, obstruction, reduced perfusion | eGFR is an estimate — less reliable at extremes of age and body size. A fall of ≥25% from baseline = significant. Trend matters more than a single value. Stage CKD using eGFR + ACR together. CKD eGFR Staging: G1 ≥90 · G2 60–89 · G3a 45–59 · G3b 30–44 · G4 15–29 · G5 <15 mL/min/1.73m². Stage G3b and below: refer to nephrology or follow NICE CKD pathway. G5 = preparation for renal replacement therapy. |
| Urea | Protein metabolism and renal excretion | 2.5–7.8 mmol/L | Renal failure, dehydration, high protein diet, GI bleeding (urea rises from blood digestion), Addison's, catabolism (sepsis, surgery) | Liver failure (reduced urea production), low protein diet, pregnancy (dilutional) | Urea:creatinine ratio >100 suggests upper GI bleeding or dehydration (urea disproportionately elevated). Urea rises faster than creatinine in dehydration — useful early marker of pre-renal AKI. |
🫀 Liver Function Tests (LFTs)
| Test | What It Measures | Normal Range | Causes of HIGH | Causes of LOW | ⚠️ Be Mindful Of |
|---|---|---|---|---|---|
| ALT (Alanine Aminotransferase) | Liver cell injury — most specific to liver | 7–56 U/L | Viral hepatitis (can be very high, >1000), NAFLD/NASH, alcohol, drugs (statins, methotrexate, paracetamol OD), autoimmune hepatitis, ischaemic hepatitis | Not clinically significant when low | ALT >3× ULN on statins → consider stopping. ALT >10× ULN = significant hepatitis — urgent referral. NAFLD is the most common cause of mildly elevated ALT in UK GP. |
| AST (Aspartate Aminotransferase) | Cell injury — liver AND cardiac/skeletal muscle | 10–40 U/L | Same as ALT, but also raised in MI, rhabdomyolysis, haemolysis, vigorous exercise | Not clinically significant when low | AST:ALT ratio >2:1 suggests alcohol-related liver disease. Check CK if AST elevated but ALT normal — may be muscle source, not liver. |
| ALP (Alkaline Phosphatase) | Liver / bone / placenta enzyme | 30–120 U/L (varies by age/sex) | Liver: bile duct obstruction, cholestasis, primary biliary cholangitis, hepatic metastases. Bone: Paget's disease, bone metastases, osteomalacia, healing fractures, hyperparathyroidism | Hypothyroidism, pernicious anaemia, zinc deficiency | ALP raised + GGT raised = liver source. ALP raised + GGT normal = BONE source. ALP physiologically raised in children (bone growth), pregnancy (placenta), post-fracture. Always check GGT alongside ALP. |
| GGT (Gamma-Glutamyl Transferase) | Hepatocellular function and bile duct integrity | M: 10–71 U/L F: 6–42 U/L | Alcohol (very sensitive), liver disease (all types), drugs (phenytoin, carbamazepine, rifampicin), NAFLD, biliary obstruction | Not clinically significant when low | GGT is sensitive but not specific — raised by many drugs and by alcohol. An isolated raised GGT does not equal serious liver disease. Always ask about alcohol and medication use before investigating further. |
| Bilirubin (total) | Breakdown product of haem — reflects liver processing and haemolysis | 3–20 µmol/L | Pre-hepatic: haemolysis, ineffective erythropoiesis. Hepatic: hepatitis, liver failure. Post-hepatic: gallstones, pancreatic mass, cholangiocarcinoma. Also Gilbert's syndrome (benign) | Not clinically significant when low | Bilirubin >50 µmol/L usually causes visible jaundice. Isolated raised bilirubin + normal LFTs in a fasting young person = Gilbert's syndrome (benign, common). Bilirubin rising rapidly in a jaundiced patient = urgent — rule out obstruction and liver failure. |
| Albumin | Main serum protein — made in liver; reflects nutrition and liver synthetic function | 35–50 g/L | Dehydration (relative / factitious) | Chronic liver disease, malnutrition, nephrotic syndrome, malabsorption, sepsis/acute illness (negative acute phase reactant), protein-losing enteropathy, malignancy | Low albumin = poor synthetic function, malnutrition, or protein loss. Affects drug protein binding — check free drug levels for highly protein-bound drugs (e.g., phenytoin). Corrected calcium must be calculated when albumin is low. |
🦴 Bone Profile & Metabolic Tests
| Test | Normal Range | Causes of HIGH | Causes of LOW | ⚠️ Be Mindful Of |
|---|---|---|---|---|
| Calcium (total) | 2.2–2.6 mmol/L | Primary hyperparathyroidism (most common in GP), malignancy (bony mets, PTHrP), sarcoidosis, vitamin D toxicity, thiazide diuretics, milk-alkali syndrome | Hypoparathyroidism (post-thyroidectomy), vitamin D deficiency, CKD, hypomagnesaemia, malabsorption, acute pancreatitis | Always correct for albumin: corrected Ca = measured Ca + 0.02 × (40 − albumin). Symptoms of hypercalcaemia: "Bones, Stones, Moans, Groans" (bone pain, renal stones, constipation/nausea, depression/confusion). Ca >3.0 = urgent management. |
| Phosphate | 0.8–1.5 mmol/L | Renal failure (CKD — reduced excretion), hypoparathyroidism, acromegaly, vitamin D toxicity | Hyperparathyroidism, vitamin D deficiency, malabsorption, refeeding syndrome, antacid overuse (binds phosphate) | Refeeding syndrome: phosphate, potassium, and magnesium all drop dangerously when malnourished patients start eating again — essential to monitor and replace. |
| Uric acid (urate) | M: 200–430 µmol/L F: 140–360 µmol/L | Gout, high purine diet, alcohol, diuretics (thiazides and loop), CKD, leukaemia, myeloma, cytotoxic therapy (tumour lysis), psoriasis | Allopurinol/uricosuric drugs, low purine diet, Wilson's disease (Fanconi syndrome) | Uric acid is not raised in all gout attacks — a normal level during an acute attack does not exclude gout. Diagnosis of acute gout is clinical. Check urate 4–6 weeks after acute attack for baseline and to guide allopurinol target (<360 µmol/L, or <300 if severe). |
🍬 Glucose, Diabetes & Thyroid
| Test | Normal Range | Abnormal / Causes HIGH | Causes LOW / Notes | ⚠️ Be Mindful Of |
|---|---|---|---|---|
| Fasting glucose | <6.1 mmol/L | Diabetes (≥7.0), pre-diabetes (6.1–6.9), acute stress response, Cushing's, steroids, acromegaly, phaeochromocytoma | Hypoglycaemia (<4.0): insulin excess (overdose, insulinoma), sulphonylureas, prolonged fasting, Addison's, liver failure | Two abnormal fasting results needed to diagnose diabetes in asymptomatic patients. Stress hyperglycaemia during acute illness does not equal diabetes — recheck when well. Always check in context of symptoms and other tests (HbA1c). |
| HbA1c | <42 mmol/mol (<6.0%) | Diabetes ≥48 (6.5%); pre-diabetes 42–47; raised by: poor diabetic control, haemoglobinopathy C and E, iron deficiency, B12 deficiency | Haemolytic anaemia, recent blood transfusion, erythropoietin therapy (all falsely lower HbA1c) | Invalid in: haemolytic anaemia, recent transfusion, haemoglobinopathy (HbS, HbC), pregnancy. Do NOT use HbA1c for acute-onset type 1 diabetes — in rapidly evolving T1D, HbA1c may be normal despite dangerously high glucose (not enough time for glycation). Do NOT use in pregnancy — use fasting glucose/OGTT instead (gestational diabetes uses different diagnostic criteria). HbA1c reflects average glucose over ~3 months (life of red cell). |
| TSH (Thyroid Stimulating Hormone) | 0.4–4.0 mU/L | ↑ TSH = hypothyroidism (pituitary signal telling thyroid to work harder). Causes: Hashimoto's thyroiditis, post-thyroid ablation, lithium, amiodarone | ↓ TSH = hyperthyroidism OR excessive levothyroxine. Causes: Graves' disease, toxic nodular goitre, amiodarone, subacute thyroiditis, TSH-secreting tumour (rare) | Avoid checking TSH within 4–6 weeks of levothyroxine dose change. TSH alone is sufficient for most monitoring — add free T4 only if TSH abnormal or central hypothyroidism suspected. Subclinical hypothyroidism: TSH 5–10, normal fT4, consider treating if symptomatic or TSH >10. |
| Free T4 (fT4) | 9–22 pmol/L | Hyperthyroidism, excess levothyroxine, T4-producing tumour | Hypothyroidism (primary), pituitary failure (central hypothyroidism), severe non-thyroidal illness | Central hypothyroidism (rare): TSH low or normal + low fT4. Occurs with pituitary disease — do NOT simply adjust levothyroxine dose based on TSH alone in these patients. Always check fT3 in amiodarone-related thyroid disease. |
❤️ Lipids & Cardiovascular Markers
| Test | Target / Normal | HIGH = concern when | LOW = concern when | ⚠️ Be Mindful Of |
|---|---|---|---|---|
| Total cholesterol | <5.0 mmol/L (optimal) | Primary hypercholesterolaemia, FH, hypothyroidism, nephrotic syndrome, DM, steroids, alcohol | Severe liver disease, malnutrition, hyperthyroidism (rarely clinically significant) | Treat based on QRISK3 ≥10%, not total cholesterol alone. FH (Familial Hypercholesterolaemia): TC >7.5 + family history → refer to lipid clinic. Fasting not required for routine lipid screening. |
| Non-HDL cholesterol | <2.5 mmol/L on statins (NICE target) | Poor LDL and VLDL control | — | Non-HDL is now preferred monitoring target on statins over LDL — better predictor of CV risk. Aim for ≥40% reduction from baseline, AND non-HDL <2.5 mmol/L. |
| Triglycerides | <1.7 mmol/L (optimal) | DM (poorly controlled), alcohol, obesity, hypothyroidism, renal disease, drugs (steroids, beta-blockers, thiazides), genetic hypertriglyceridaemia | Hyperthyroidism, malnutrition (rarely significant) | Triglycerides >10 mmol/L = significant pancreatitis risk — urgent lifestyle advice and consider fibrates. Non-fasting sample may be 20–30% higher than fasting value. Always check when assessing metabolic syndrome. |
| CRP (C-Reactive Protein) | <5 mg/L | Infection (bacterial typically >50–100), inflammation (any cause), tissue injury, malignancy, MI (mild rise). Very high (>200): severe bacterial infection or major tissue damage | Not clinically significant when low (rules out significant inflammation) | CRP rises within 6–12 hours, peaks at 48h, falls with resolution. AKT caveat: a normal CRP does NOT exclude serious disease when pre-test probability is high — early infection, localised infection (e.g. early appendicitis), or some malignancies may not raise CRP initially. Useful in monitoring treatment response (e.g., antibiotics in CAP). Point-of-care CRP <20 mg/L in respiratory infection significantly reduces antibiotic prescribing — use it! |
| ESR (Erythrocyte Sedimentation Rate) | M: <15 mm/hr; F: <20 mm/hr (rises with age) | Giant cell arteritis (typically >50 — do not wait for ESR to treat!), myeloma (very high), infection, inflammation, malignancy, pregnancy, anaemia, connective tissue disease | Polycythaemia (relatively low) | ESR is non-specific but sensitive. ESR >100 mm/hr: think myeloma, malignancy, severe infection, giant cell arteritis. A normal ESR does NOT exclude GCA — treat clinically if clinical suspicion is high. ESR rises physiologically with age and in pregnancy. |
💊 Haematinics & Iron Studies
| Test | Normal Range | HIGH = suggests | LOW = suggests | ⚠️ Be Mindful Of |
|---|---|---|---|---|
| Ferritin | M: 30–400 µg/L F: 13–150 µg/L | Iron overload (haemochromatosis), infection/inflammation (acute phase reactant), liver disease, haemolysis, malignancy (especially lymphoma, hepatoma) | Iron deficiency — the most specific marker of iron stores. Low ferritin = iron deficiency, regardless of Hb. Ferritin <12 µg/L = absent iron stores (strongly confirms deficiency). Ferritin <30 µg/L = depleted stores (treat as iron deficiency). | Ferritin is an acute phase protein — it is ELEVATED by inflammation even when iron stores are low. A ferritin in the "normal range" does not exclude iron deficiency if CRP is elevated. Ferritin >1000 µg/L with no clear cause → consider haemochromatosis, haematological malignancy, liver disease. |
| Serum iron + TIBC | Serum Fe: 10–30 µmol/L TIBC: 45–72 µmol/L | Iron overload, liver disease releasing stored iron (TIBC low), haemochromatosis | Iron deficiency: low serum iron + high TIBC + low saturation (<20%) | Iron studies are affected by time of day (morning higher), diet, and acute illness. Ferritin is more reliable for screening than serum iron alone. Transferrin saturation <20% confirms iron deficiency when ferritin is equivocal. |
| Serum B12 | 180–900 pmol/L (varies) | Myeloproliferative disorders, supplementation, liver disease | Pernicious anaemia, vegan/vegetarian diet, malabsorption, metformin use, nitrous oxide use (active B12 + MMA more reliable in this case) | Normal serum B12 does not exclude functional deficiency. Use methylmalonic acid (MMA) or homocysteine if clinical suspicion remains high. Do NOT use active B12 if patient uses recreational nitrous oxide. Treat immediately if neurological symptoms — do not wait for full workup. |
| Folate (serum) | >7 nmol/L | Folate supplementation | Dietary deficiency (poor diet, alcohol), malabsorption (coeliac, Crohn's), drugs (methotrexate, phenytoin, trimethoprim), pregnancy (demand increases) | Always give folic acid 400–5000 µg preconceptually and in first trimester (5mg if previous NTD, DM, or epilepsy). Folate deficiency causes macrocytic anaemia — but NOT neurological damage (unlike B12). Never treat B12 deficiency with folate alone — risks masking neuropathy. |
🔬 Tumour Markers & Miscellaneous
| Test | What It Measures / Normal | HIGH = suggests | LOW | ⚠️ Be Mindful Of |
|---|---|---|---|---|
| PSA (Prostate Specific Antigen) | Age-specific upper limits (commonly used UK pathways): 40–49: ~2.5 ng/mL 50–59: ~3.5 ng/mL 60–69: ~4.5 ng/mL 70–79: ~6.5 ng/mL | Prostate cancer (but NOT diagnostic), BPH, prostatitis, UTI, post-ejaculation, post-DRE, post-catheterisation, vigorous cycling | 5-alpha reductase inhibitors (finasteride) halve PSA — account for this (multiply by 2 when adjusting) | PSA is NOT a diagnostic test for prostate cancer. A raised PSA + clinical suspicion → refer via 2WW for mpMRI prostate + urology assessment. Do NOT test PSA during active symptomatic UTI or within 48h of ejaculation or DRE — gives false elevation. Advise no ejaculation 48h and no vigorous cycling before test. PSA should not be tested in asymptomatic men without informed consent and discussion of limitations. |
| CA125 | <35 U/mL | Ovarian cancer (but non-specific — raised in endometriosis, PID, fibroids, any peritoneal irritation, heart failure, liver disease) | Not significant when low | NICE NG12: check CA125 in women with persistent/frequent bloating, pelvic pain, feeling full, IBS-type symptoms >12×/month. If CA125 ≥35, arrange USS pelvis. Do NOT use in isolation — combine with clinical history and USS. Sensitivity for early ovarian cancer is low. |
| CK (Creatine Kinase) | M: 24–195 U/L F: 24–170 U/L | Myocardial infarction (CK-MB), rhabdomyolysis (very high — renal risk), polymyositis/dermatomyositis, Duchenne muscular dystrophy, statin myopathy, hypothyroidism, heavy exercise | Not significant when low | Statin-related myopathy: CK >4× ULN + symptoms → stop statin. If CK normal but patient has myalgia, still consider statin-related — CK can be normal in statin myopathy. CK >10× ULN = risk of rhabdomyolysis → urgent — IV fluids to protect kidneys. |
| Troponin (I or T) | High-sensitivity Troponin T (hsTnT): <14 ng/L | ACS (myocardial damage), myocarditis, PE (right heart strain), heart failure (demand ischaemia), renal failure, sepsis (demand ischaemia), cardiac contusion | Not significant when low (effectively rules out ACS in low-risk patients if normal at 0h and 3h) | Single troponin alone is insufficient. Use 0h and 3h (or 0h and 1h if high-sensitivity) serial measurements. Rising pattern = ACS. Chronically elevated but stable = non-ACS cause (CKD, heart failure). In GP: any chest pain with possible ACS features → 999 or same-day A&E. |
| D-dimer | <0.5 mg/L (lab-specific) | VTE (DVT, PE), DIC, infection/sepsis, malignancy, surgery/trauma, pregnancy, liver disease, AF, heart failure | Not significant when low — a NEGATIVE D-dimer in LOW pre-test probability RULES OUT VTE effectively | D-dimer is only useful as a RULE-OUT test in LOW pre-test probability patients. Do NOT use in high-probability patients (Wells score ≥4 for PE, ≥3 for DVT) — go straight to imaging. False positives everywhere: cancer, pregnancy, infection, recent surgery. A positive D-dimer means nothing without clinical context. |
| INR / PT | INR 0.9–1.2 (therapeutic target varies by indication) | Warfarin effect, liver disease (reduced clotting factor production), vitamin K deficiency, DIC, factor deficiencies | Hypercoagulable state (rarely tested this way) | Warfarin AF target INR: 2.0–3.0. Mechanical heart valve: typically 2.5–3.5. INR >5 without bleeding: reduce/hold dose. INR >8 or bleeding: urgent reversal. INR affected by many drugs — check interactions every time a new medication is started in a warfarin patient. |
Unexplained thrombocytosis (raised platelets) in a patient over 40, particularly when persistent, should prompt consideration of an underlying malignancy — especially GI cancer, lung cancer, or lymphoma. Iron deficiency is the most common benign cause, but always ask: why is this patient iron deficient? And if platelets remain elevated after treating iron deficiency, investigate further. NICE NG12 now specifically lists unexplained raised platelets as a symptom warranting investigation for certain cancers.
Section 6
💧 Urine Tests
Not just for UTIs. Urine tells you an enormous amount — if you interpret it in context.
Urine Dipstick — The Key Rules
- Dipstick is a screening tool, not a diagnostic test
- Positive nitrites AND leucocytes in a symptomatic patient → treat for UTI
- Positive dipstick in an asymptomatic patient = asymptomatic bacteriuria → do NOT treat (except in pregnancy)
- Haematuria on dipstick: if confirmed on repeat, investigate (age ≥40 → urgent suspected cancer pathway if visible haematuria)
- Proteinuria on dipstick: quantify with ACR (albumin:creatinine ratio) — send early morning urine
- Glucose on dipstick: check HbA1c — may be diabetes or benign renal glycosuria
⚠️ Common Dipstick Traps
- Treating asymptomatic bacteriuria in non-pregnant adults — this causes antibiotic resistance and does not benefit the patient
- Using a dipstick to diagnose UTI in catheterised patients — always symptomatic before treating
- Ignoring confirmed visible haematuria — this is a red flag requiring urgent investigation regardless of how well the patient appears
- Missing proteinuria in a diabetic patient because the dipstick showed only "trace" — use ACR to quantify
| Urine Test | Purpose | Key Clinical Points |
|---|---|---|
| MSU (Mid-stream Urine) | Diagnosis of UTI / bacteriuria | Only useful if interpreted with symptoms. Send before antibiotics if possible. |
| ACR (Albumin:Creatinine Ratio) | CKD monitoring, diabetic nephropathy | Use early morning urine for most accurate result. ACR >3 mg/mmol = microalbuminuria. >30 = macroalbuminuria. |
| Urine pregnancy test (hCG) | Diagnosis of pregnancy (including ectopic) | Positive from ~10 days after conception. Quantitative serum hCG more accurate in ectopic workup. |
| 24hr urine collection | Precise measurement of protein, creatinine clearance | Largely replaced by ACR in modern primary care practice but still used for certain conditions. |
| Urine cytology | Haematuria investigation | Not first-line in GP. Usually done after referral for haematuria clinic assessment. |
| First-void urine (FVU) | STI screening (chlamydia, gonorrhoea NAAT) | First 10–20 mL of urine at start of micturition captures most organisms from urethra. |
Section 7
📈 ECG in GP
You will not be asked to interpret a complex EP study. But you will be expected to recognise the patterns that change management.
A Systematic Approach — Every Time
Step through this in order:
- Rate — 300 ÷ number of large squares between R waves
- Rhythm — regular or irregular? P waves present?
- Axis — normal: I positive, aVF positive
- P waves — present, shape, 1:1 relationship with QRS?
- PR interval — normal: 3–5 small squares (120–200ms)
- QRS width — normal: <3 small squares (<120ms)
- ST segment — elevation or depression?
- T waves — inversion, tall, or flattened?
- QTc — prolonged if >440ms in men, >460ms in women
The 23 patterns every GP must recognise:
- Atrial fibrillation (AF) — irregularly irregular rhythm, absent P waves, chaotic baseline
- Atrial flutter — regular "sawtooth" flutter waves at ~300 bpm, ventricular rate typically 150 bpm (2:1 block); may look like tachycardia if rate rapid
- SVT — Supraventricular Tachycardia — narrow complex tachycardia, rate 150–250 bpm, P waves absent or buried in QRS; abrupt onset and termination
- Ventricular Tachycardia (VT) — broad complex tachycardia (QRS >120ms), rate >100 bpm, AV dissociation; treat as VT until proven otherwise
- STEMI — ST elevation ≥1mm in ≥2 contiguous limb leads or ≥2mm in V1–V3; always check for reciprocal depression in opposite leads
- LBBB — QRS >120ms, broad notched R in I, V5, V6; deep S in V1; absence of septal Q waves — new LBBB = STEMI equivalent, call 999
- RBBB — QRS >120ms, RSR' ("M-shape") in V1–V2, broad S wave in I and V6; isolated RBBB often benign but new RBBB with symptoms needs investigation
- 1st degree heart block — PR interval >200ms (5 small squares); every P followed by QRS; usually benign but can indicate drug toxicity (digoxin, beta-blockers) or inferior MI
- 2nd degree heart block — some P waves not followed by QRS; Mobitz I (Wenckebach): progressively lengthening PR until a beat is dropped; Mobitz II: fixed PR with sudden dropped beat — Mobitz II carries risk of complete heart block
- Complete (3rd degree) heart block — P waves and QRS completely dissociated; regular slow ventricular escape rate (20–40 bpm); requires urgent pacing
- Prolonged QTc — QTc >440ms (men) / >460ms (women); risk of torsades de pointes; causes include drugs (macrolides, antipsychotics, sotalol), electrolyte imbalance, congenital LQTS
- LVH — Left Ventricular Hypertrophy — tall R waves in V5/V6 (≥25mm) or deep S in V1/V2; Sokolow-Lyon criteria: S(V1) + R(V5/V6) ≥35mm; associated with hypertension and aortic stenosis; may show ST depression and T-wave inversion ("strain pattern")
- RVH — Right Ventricular Hypertrophy — dominant R wave in V1 (R≥S), right axis deviation, T-wave inversion V1–V4; causes include COPD, pulmonary hypertension, mitral stenosis, PE
- Angina / Ischaemia (non-STEMI pattern) — ST depression ≥1mm (horizontal or downsloping is most significant), T-wave inversion or flattening; may be dynamic (changes with symptoms); lateral ischaemia common in V4–V6
- Cardiomyopathy — no single pattern; look for: poor R-wave progression across precordial leads (dilated CMP), voltage criteria for LVH + asymmetric septal hypertrophy (HCM), widespread low voltages or pseudo-infarct Q waves (restrictive/infiltrative); always interpret with clinical context
- Peaked T waves / hyperkalaemia — tall symmetrical tent-shaped T waves (especially precordial leads), widening QRS, eventually sine-wave pattern; ECG change is an emergency — check potassium urgently
- Torsades de Pointes — polymorphic VT where the QRS complexes appear to "twist" around the isoelectric baseline; rate 200–250 bpm; always preceded by prolonged QTc. May self-terminate but can degenerate into VF. Treat with IV magnesium sulphate; identify and correct the cause (drugs, electrolytes)
- Pericarditis — widespread saddle-shaped (concave upward) ST elevation across multiple leads not confined to a single coronary territory; PR depression (most specific sign, especially in II and V4–V6); absence of reciprocal ST depression distinguishes it from STEMI. May recur
- Pericardial Effusion — low voltage QRS in all leads (<5mm in limb leads, <10mm in precordial leads); electrical alternans (alternating QRS height on consecutive beats — heart swinging in fluid) is pathognomonic when present and raises concern for tamponade; sinus tachycardia common
- Mitral Stenosis — P mitrale: broad, notched (bifid) P waves in lead II (>0.12s), biphasic P in V1 (LA enlargement); AF is a very common complication; RVH features may develop if pulmonary hypertension supervenes
- Mitral Regurgitation — LVH features (volume overload); broad P waves (P mitrale); AF frequent due to LA dilatation; left axis deviation; ECG alone cannot confirm — echocardiography is the key diagnostic investigation
- Aortic Stenosis — LVH with strain pattern: ST depression and T-wave inversion in lateral leads (I, aVL, V5–V6); left axis deviation; sometimes LBBB; severe AS may produce progressively worsening LVH on serial ECGs
- Aortic Regurgitation — LVH (diastolic overload pattern): tall broad R waves in V5/V6, deep S in V1; deep Q waves may appear in lateral leads; left axis deviation; again, echocardiography is the diagnostic gold standard
- Pulmonary Embolism (PE) — the classic S1Q3T3 pattern (deep S in I, Q wave in III, inverted T in III) is present in only ~10–20% of PE cases — it is not a reliable screening sign. Sinus tachycardia is the most common ECG finding (~70%); other features include RBBB (complete or incomplete), T-wave inversion V1–V4 (right heart strain), and right axis deviation. A normal ECG does not exclude PE. The ECG in PE is useful for excluding other diagnoses (STEMI, LBBB) and for risk stratification, not for ruling PE in or out
| ECG Finding | Likely Cause in GP | Action |
|---|---|---|
| AF (new) | Hypertension, valve disease, thyrotoxicosis, alcohol, idiopathic | Check TFTs, echo. Rate or rhythm control. CHADSVASC2 → anticoagulation if score ≥2 (men) or ≥3 (women). |
| ST elevation | STEMI, pericarditis, Brugada, LBBB | Call 999 immediately if STEMI or new LBBB. Do not delay for further tests. |
| ST depression / T wave inversion | NSTEMI, strain pattern (LVH), digoxin effect, electrolyte disturbance | Correlate with symptoms. Troponin if chest pain. Urgent cardiology if dynamic changes. |
| Prolonged QTc | Drugs (clarithromycin, antipsychotics, sotalol, amiodarone, domperidone), electrolyte imbalance, congenital LQTS | Review all medications. Check electrolytes. Avoid QT-prolonging drugs. Refer if QTc >500ms. |
| First degree heart block | Athletic heart, vagal tone, inferior MI, drugs (digoxin, beta-blockers) | Usually benign. Review medications if new. No specific treatment usually needed. |
| RBBB | Normal variant, PE, right heart strain, congenital | Isolated RBBB is often benign. New RBBB in context of chest pain or breathlessness → investigate. |
Most GP surgeries now have 12-lead ECG capability. Have a low threshold for performing one in: chest pain, palpitations, unexplained syncope, breathlessness, new hypertension, or before starting drugs that affect QTc (e.g., antipsychotics). An ECG takes 5 minutes and could save a life.
Section 8
🫁 Spirometry
The respiratory equivalent of an ECG — essential for diagnosing and staging COPD and asthma.
Spirometry can generally be performed reliably from age 5–6 years in cooperative children, though results are more reproducible from around 7 years. Children under 5 typically cannot maintain the prolonged forced expiratory manoeuvre required for valid FVC/FEV1 measurements. For younger children, tidal breathing techniques (such as the raised volume rapid thoracic compression technique) are used in specialist settings, not in GP. In primary care, spirometry is most commonly performed in adults; referral to paediatric respiratory services is appropriate for younger children with suspected obstructive or restrictive disease.
Key Spirometry Measures
- FVC — Forced Vital Capacity (total air exhaled on forced breath)
- FEV1 — Forced Expiratory Volume in 1 second
- FEV1/FVC ratio — the key diagnostic ratio
- PEFR — Peak Expiratory Flow Rate (for asthma monitoring)
Interpreting the Ratio
| Pattern | FEV1/FVC | Example |
|---|---|---|
| Normal | ≥0.70 (≥70%) | Normal spirometry |
| Obstructive | <0.70 (<70%) | COPD, asthma |
| Restrictive | ≥0.70 but FVC ↓ | Pulmonary fibrosis, obesity |
| Mixed | <0.70 and FVC ↓ | Advanced COPD with fibrosis |
COPD Severity (GOLD Criteria) — FEV1 % Predicted
| Grade | Severity | FEV1 % Predicted |
|---|---|---|
| GOLD 1 | Mild | ≥80% |
| GOLD 2 | Moderate | 50–79% |
| GOLD 3 | Severe | 30–49% |
| GOLD 4 | Very severe | <30% |
- Spirometry must be performed with correct technique and by trained personnel
- Reversibility testing (post-bronchodilator spirometry) helps differentiate asthma from COPD
- Do NOT perform spirometry during an acute exacerbation — wait at least 4–6 weeks for the patient to recover
- In asthma, spirometry may be normal between attacks — diagnose on clinical grounds + variable peak flow
Section 9
🔬 Other Investigations in GP
Beyond blood tests and ECGs — a quick reference to the investigations you will encounter in clinical practice and exams.
| Investigation | Key GP Indications | Important Points |
|---|---|---|
| Cervical Smear (HPV primary screening) | All eligible women aged 25–64 (every 3–5 years per programme) | HPV primary screening since 2019. Smear collected for cytology only if HPV positive. Know technique: spatula + endocervical brush (or liquid-based cytology device). |
| Blood glucose (point-of-care) | Suspected hypoglycaemia, acute illness monitoring in diabetics, initial assessment of possible DKA | Finger-prick BG: rapid, immediate. Document clearly. Treat hypoglycaemia (BG <4 mmol/L in symptomatic patient) immediately. |
| ABPI (Ankle-Brachial Pressure Index) | Assessment of peripheral arterial disease before compression bandaging in leg ulcers | ABPI <0.8 = significant arterial disease. Do NOT apply compression bandaging if ABPI <0.8 — this can cause ischaemia. |
| 24-hour BP monitoring (ABPM) | Confirming hypertension diagnosis, white-coat hypertension, assessing treatment | NICE recommends ABPM to confirm hypertension before treatment. Clinic BP ≥140/90 → ABPM. ABPM ≥135/85 = confirmed hypertension. |
| eGFR monitoring | CKD staging and monitoring, medication dose adjustment | eGFR from CKD-EPI or MDRD equations. Used in conjunction with ACR for CKD staging and referral decisions. |
| Stool tests (H. pylori antigen, calprotectin) | H. pylori: dyspepsia management. Faecal calprotectin: IBS vs IBD differentiation before colonoscopy. | Stool H. pylori antigen: test 4 weeks after completing eradication. Calprotectin <50 μg/g makes IBD unlikely. |
| Hepatitis serology | Risk assessment (IV drug use, sexual exposure, travel), pre-vaccination titres, follow-up after treatment | Remember: HBsAg (surface antigen) = current infection. Anti-HBs = immunity. HBeAg = high infectivity. |
Section 10
🚨 Red Flags — Investigations You Must Not Miss
🚨 Results That Require Urgent Action
- Potassium >6.5 mmol/L — risk of fatal arrhythmia. ECG immediately. Same-day assessment.
- Sodium <120 or >155 mmol/L — risk of seizure, coma. Urgent management.
- Calcium >3.0 mmol/L — symptomatic hypercalcaemia. Rehydrate. Investigate urgently.
- STEMI or new LBBB on ECG — call 999 immediately. Do not manage in primary care.
- ST elevation + chest pain — do not delay for repeat ECG. Same action.
- Hb <70 g/L — discuss urgently. Consider same-day haematology / A&E depending on symptoms.
- Visible haematuria (any age, no UTI) — urgent urology referral (2-week wait).
- INR >10 — reversal needed. Discuss urgently with haematology/anticoagulation service.
- Troponin rising pattern — even mildly elevated troponin in symptomatic patient = ACS until proven otherwise.
- Bilirubin rapidly rising + jaundice — may indicate decompensated liver disease or biliary obstruction. Urgent.
- BG <4 mmol/L + altered consciousness — treat immediately. Do not wait for lab result.
- Ferritin >1000 μg/L (unexplained) — consider haemochromatosis, haematological malignancy, or severe systemic disease.
Many GP practices now use automated systems to alert patients to results. But you must have a clear system for who reviews abnormal results, who contacts the patient, and within what timeframe. A dangerous result that sits in an inbox unreviewed for a week is a medico-legal nightmare — and, more importantly, it can harm the patient.
Section 21 — Trainee Voices & Educator Insights
🏕️ From the Trenches
What trainees, trainers, and GP educators actually say — the stuff that does not appear in the guidelines, but is the stuff you most need to know.
The insights below are drawn from real patterns observed across GP trainee forums, GP educator discussions, peer-reviewed GP training research, and UK primary care teaching resources. All clinical content has been cross-checked against official guidance. Nothing here contradicts RCGP, NICE, or GMC guidance — these are the things that add to it, not replace it.
🏥 The Hospital Habits Problem
Trainees arriving from hospital posts often order investigations the way they were taught on the wards: "FBC, U&E, LFTs, CRP, glucose, bone profile, TFTs" — the whole lot, reflexively, for any patient who seems a bit under the weather. In hospital, this made sense. In GP, it generates anxiety, false positives, and a cascade of repeat tests that occupies the practice for weeks. Experienced GP trainers call this "hospital habits" — and breaking them is one of the first real learning curves of GP training.
When a trainer reviews your consultation and sees a full 10-test screen for a 35-year-old with mild tiredness and no red flags, they are not thinking "good, thorough doctoring." They are thinking: "Why did we need all of these? What question were each of these answering?" If you cannot answer that question for every individual test, the test probably was not needed. This is what the AKT and SCA test — not whether you ordered everything, but whether you ordered the right things.
One well-known piece of advice from GP trainers across multiple deaneries: "If you are ordering a test to reassure yourself rather than to answer a clinical question, that is a red flag about your own reasoning — not a safety net." Tests ordered out of anxiety have a habit of coming back borderline-abnormal, generating more anxiety, more tests, and occasionally a frightened patient with no actual disease.
📊 The Over-Testing Reality — What the Research Shows
What a University of Bristol Study Found
- Over 100 million blood tests are ordered by GPs in England every year
- Only 6.2% of blood tests led to a new diagnosis or confirmed a diagnosis
- Around a quarter (26.6%) of patients had results entirely in the normal range
- A quarter of tests were assessed as partially or fully unnecessary when reviewed retrospectively
- Around half of tests did not lead to any change in management or reassurance
Source: Watson J et al, BJGP / Bristol PACT study, 2023
What GPs Actually Say About It
Real voices captured in a UK GP audit of testing practice (BMC Primary Care):
- "I regard the over-investigation of essentially well patients on an annual basis as a simply scandalous waste of NHS resource."
- "The harms and distress caused by testing and explaining minor abnormalities is huge."
- "I am overwhelmed with all the routine monitoring — it has risen massively over the 20+ years I have been qualified."
Source: GP perspectives audit, BMC Primary Care 2020
This is not an argument to under-investigate. It is an argument to think before you test. The SCA rewards trainees who explain their reasoning out loud to the patient. "I'm going to check your thyroid because that can cause exactly these symptoms" scores marks. "I'll just do some routine bloods" scores none — and in real life, it generates weeks of workload for the practice.
📱 Online Results Access — The New GP Challenge
What Changed in 2023
From April 2023, the GP contract in England requires practices to give patients online access to their prospective records — including test results. This means patients now often see their results before their GP has reviewed and actioned them. This is a significant shift in how results communication works.
What trainees need to know:
- Patients may contact the practice having already seen an "abnormal" result and be frightened before you have reviewed it
- A computer-generated flag saying "abnormal" may be clinically insignificant — but the patient does not know that
- Your explanation of what a result means has become more important than ever, not less
- When ordering tests, tell the patient explicitly when to expect the result and what to do if they see something alarming before you have called them
What patients actually want (research finding):
- Patients find a text saying "all normal, no further action" insufficient for ongoing problems — they want to know what it means
- Patients want to know why a test was done and what a normal result actually tells them
- Patients who have a clear follow-up plan report significantly less anxiety while waiting for results
- The phrase "take the worry out of the wait" is used by patients to describe a good pre-test explanation
Source: Watson et al, BJGP qualitative study 2022
Tell the patient three things before every test: (1) why you are doing it, (2) when to expect the result, and (3) what to do if they see something unexpected before you call them. This single habit reduces callbacks, reduces anxiety, and — in the SCA — demonstrates exactly the kind of patient-centred communication that examiners are looking for.
🔍 The Context Trap — Interpreting Results in Isolation
Trainees (and sometimes AKT questions) present a single abnormal value and ask: "What do you do?" The most common error is treating the number in isolation rather than in context. An eGFR of 45 in a 70-year-old with long-standing CKD on ramipril is almost certainly fine — it may be their baseline. The same eGFR in a previously healthy 35-year-old who started ibuprofen last week is a medical problem that needs acting on immediately.
| Result | Context A — Often Benign | Context B — Needs Action |
|---|---|---|
| K+ 5.3 mmol/L | Known CKD patient, stable, same as last month, well-looking sample | New result, no known CKD, patient on ACEi, possibly haemolysed → confirm and act |
| eGFR 45 | CKD3 patient, stable for 2 years, no new medications | Previously normal, started NSAIDs last week, vomiting → AKI until proven otherwise |
| TSH 0.1 mU/L | Patient on levothyroxine, dose was just increased last week | Not on treatment, recent onset palpitations and tremor → hyperthyroidism, investigate urgently |
| ALT 65 U/L (mildly raised) | Recent heavy weekend, repeat normal in 6 weeks | Persistent for 3 months, patient on methotrexate → hepatotoxicity, review medication |
| Hb 105 g/L | Chronic inflammatory disease, stable over several results | New finding in a 62-year-old man, no obvious cause → must investigate GI source |
In GP, results should always be viewed in trend, not snapshot. A creatinine of 120 that was 80 last month is more alarming than a creatinine of 150 that has been stable for three years. Most GP clinical systems display a graph view — use it. Trainees who look at the graph make better decisions than those who read only the latest value.
🎯 SCA Examiner Insight — Investigations and Results Cases
What SCA Examiners and Bristol Deanery Educators Say
What candidates consistently do wrong:
- Ordering tests and naming them without explaining why — sounds like box-ticking
- Delivering results as numbers: "Your haemoglobin was 99 and your MCV was 72" — meaningless to most patients
- Not checking what the patient already knows or fears before starting the explanation
- Moving straight to management before checking the patient has understood the diagnosis
- Over-investigating in the SCA because it feels "safer" — examiners see this as lack of clinical confidence
- Not mentioning who is responsible for following up the result
What candidates do that impresses examiners:
- Starting with ICE before launching into results: "How have you been since we did those tests? Did you have any thoughts about what they might show?"
- Translating results into plain language immediately: not "microcytic anaemia" but "your blood count shows your iron levels are low"
- Pausing after delivering news: "How does that sound to you?"
- Connecting the result to the patient's experience: "This explains why you've been feeling so tired"
- Being explicit about follow-up: "I will personally review the result when it comes back"
- Safety-netting with specific symptoms — not just "come back if worried"
Synthesised from Bristol GP deanery SCA guidance, SCA examiner feedback reports, and GP training educator teaching resources.
Experienced SCA trainers advise trainees to spend roughly the first 6 minutes of a results consultation on gathering information — how the patient has been, what they understand, what they are worried about — and only then move to the explanation and plan. Trainees who rush straight to delivering the result in minute one often miss crucial ICE, misjudge the patient's emotional state, and lose marks in the "Relating to Others" domain. The SCA reward goes to the doctor who listens first.
🪤 The Clinical Traps Trainees Report Most Often
🩸 Blood Test Traps
- The coeliac trap: Ordering tTGA IgA in a patient who has already been gluten-free for months. The negative result is meaningless and you have delayed the diagnosis. Always ask about diet first.
- The ferritin inflation trap: Ferritin is an acute phase protein. A "normal" or even "raised" ferritin in someone with CRP of 80 does not exclude iron deficiency. Inflammation masks a low ferritin.
- The haemolysis K+ trap: Nearly every trainee acts on a K+ of 5.5 that turns out to be a haemolysed sample. Check the lab comment. Repeat before acting.
- The levothyroxine timing trap: TSH is unreliable if tested within 4–6 weeks of a dose change. Telling a patient their dose needs adjusting based on an early recheck is a common and avoidable error.
💧 Urine / ECG / Spirometry Traps
- The catheter dipstick trap: A positive dipstick in a catheterised patient nearly always grows something. It does not mean infection. Treat the patient, not the dipstick.
- The RBBB panic trap: Many trainees refer patients urgently for isolated, incidental RBBB found on a routine ECG. Isolated RBBB in an asymptomatic patient is usually a normal variant. Correlate clinically.
- The spirometry mid-exacerbation trap: Performing spirometry on a patient who is currently wheezy or recovering from a chest infection gives misleading results. Wait 4–6 weeks post-exacerbation.
- The proteinuria single dipstick trap: One positive dipstick for protein does not equal significant proteinuria. Always confirm with an ACR on an early morning urine sample before making clinical decisions.
The D-dimer question. Many trainees know that D-dimer rules out VTE — but forget that this is only true when pre-test probability is low. A positive D-dimer in a high-probability patient means nothing — it is always positive in that group. And a D-dimer in a patient with active infection, pregnancy, or malignancy will be positive regardless of whether VTE is present. The AKT tests this nuance directly. Always apply a Wells score before reaching for D-dimer.
💊 Drug Monitoring — What Trainees Get Wrong
Methotrexate requires regular FBC and LFT monitoring — typically every 1–3 months depending on the condition and stability. The danger is not just missing the monitoring: it is not acting on a mildly elevated LFT or falling WCC because it looks "only slightly off." Methotrexate toxicity can be severe. Any significant rise in LFTs or drop in WCC on methotrexate should prompt a discussion with the prescribing specialist or haematology — not watchful waiting. Trainees often spot the abnormality but underact on it.
| Drug | What to Monitor | Frequency | The Specific Danger Trainees Miss |
|---|---|---|---|
| Methotrexate | FBC, LFTs, U&E | Every 1–3 months | Stopping monitoring when the patient "seems well" — toxicity can be silent |
| Lithium | Serum lithium, TFTs, U&E | Every 6 months (stable) | Dehydration (diarrhoea, hot weather, diuretics) causes rapid toxicity — sick day rules are essential |
| Amiodarone | TFTs, LFTs, CXR | Every 6 months | Amiodarone causes both hypo- AND hyperthyroidism — always check TFTs, not just TSH |
| ACE inhibitor / ARB | U&E, eGFR | 1–2 weeks after starting; after dose increase | Missing an AKI in a patient who also takes NSAIDs — the "triple whammy" (ACEi + diuretic + NSAID) |
| Clozapine | FBC (mandatory neutrophil count) | Weekly for 18 weeks, then 2-weekly, then monthly | This monitoring is mandatory and legally required — missing it is a serious prescribing error |
| SGLT2 inhibitors | eGFR before starting; review in CKD | Before starting; annually | Do NOT start if eGFR <45 for most indications; withhold during acute illness (euglycaemic DKA risk) |
A patient on an ACE inhibitor + diuretic who starts taking regular NSAIDs (e.g., ibuprofen for a bad back) is at high risk of AKI. This combination — called the "triple whammy" — reduces renal perfusion threefold. U&Es should be rechecked, NSAIDs should be stopped, and the patient should have sick day rules explained. This scenario appears frequently in AKT questions and occasionally in SCA cases.
🎧 From GP Educators & Teaching Sessions
Insights drawn from UK GP educator teaching resources, Primary Care Knowledge Boost podcast episodes, deanery teaching sessions, and GP trainer networks.
The journey of a urine sample matters. When you request an MSU, the clinical details you write on the form affect what the lab actually tests for. "Possible UTI" and "possible STI screen" generate completely different processing pathways. Be specific with your clinical information — it is part of the quality of the investigation request, not just an afterthought.
GP trainees who struggle with AKT data interpretation questions often fail because they try to memorise individual results rather than understanding the physiological pattern. Understanding why hyperkalaemia and hyponatraemia occur together in Addison's disease is more useful than memorising the numbers. The AKT rewards understanding over recall.
Spirometry performed poorly is worse than no spirometry at all — it generates false diagnoses. COPD has historically been overdiagnosed in primary care partly because of poor-quality spirometry technique. This is why current NICE guidance emphasises post-bronchodilator testing and the importance of trained personnel. If you are not sure the spirometry was done properly, the result cannot be trusted.
The standard of results communication in UK general practice is highly variable. GP educators consistently report that trainees underestimate how much patients value a good explanation of a normal result. "Everything was normal" is not a satisfying explanation for a patient who was tested because of a worrying symptom. "The test was reassuring — it confirms this isn't anything serious, and here is what we think is going on instead" is.
🌍 Specific Insights for International Medical Graduates (IMGs)
What IMGs Find Most Different in UK GP Investigations
Systems that are UK-specific:
- NHS cervical screening programme — HPV primary screening since 2019. Very different from smear-led systems in many other countries.
- QRISK3 — The UK tool for cardiovascular risk. Not Framingham. Not JNC. Specific to the NHS and tested in the AKT.
- eGFR-based CKD staging — combined with ACR. Some countries still use creatinine alone. UK practice uses both for staging and referral decisions.
- ABPM for hypertension confirmation — in many healthcare systems, high clinic BP equals a diagnosis. In UK GP, NICE requires ABPM to confirm. This is frequently misunderstood.
Cultural differences to be aware of:
- UK GP culture values restraint in investigation — ordering less (but better) is praised. In some healthcare systems, comprehensive testing is the expected norm.
- Patients in UK GP have increasing online access to results — this is newer than in most other countries and requires proactive explanation strategies.
- HbA1c uses mmol/mol in the UK — not the % system used in North America. Know both conversions: 48 mmol/mol = 6.5%, 42 mmol/mol = 6.0%
- Drug monitoring schedules are highly protocolised in UK GP (shared care agreements, EMIS/SystmOne alerts). Understanding how these work in practice is part of safe prescribing.
Section 15
⚠️ Common Pitfalls & Trainee Traps
Clinical Traps
- Treating a dipstick positive in an asymptomatic patient as a UTI
- Not explaining the reason for investigations to the patient (SCA fail)
- Treating haemolysed K+ without rechecking
- Diagnosing coeliac on tTGA while patient is gluten-free
- Missing that raised ALP + normal GGT = bone disease, not liver
- Ordering a D-dimer when pre-test probability is high
- Starting iron without finding the cause of the anaemia
- Not checking who is responsible for following up abnormal results
Consultation Traps
- Listing tests without explaining why — sounds like box-ticking to examiners
- Delivering results as numbers without translating them into meaning
- Skipping ICE before starting the results explanation
- Rushing past the patient's emotional reaction
- Forgetting to safety-net with specific symptoms to watch for
- Using clinical jargon like "your renal function is impaired" without explaining what that means
- Not giving a clear plan — what happens next, and when
Section 16
💎 Insider Pearls — Real-World Wisdom
Never order a test without having a system for who reviews the result. In busy GP practices, results can get lost. Document clearly who is responsible, and tell the patient what to do if they have not heard back within a set timeframe.
A mildly abnormal result in an otherwise well patient is almost always worth repeating before starting a diagnostic cascade. Many trainees learn this the hard way — after expensive and anxiety-provoking investigations for a haemolysed K+ or a borderline HbA1c in a fasted state.
Every positive test generates more tests. In primary care, where prior probabilities are low, you can create enormous anxiety and harm with an investigation that was never clearly indicated. Think before you test — not after.
Experienced GPs order fewer tests than trainees — not because they know less, but because they know more. They know which tests genuinely change management for a given presentation, and they know how to explain their clinical reasoning to patients when they choose not to test.
Section 17
👩🏫 For Trainers — Teaching Pearls
Common Trainee Blind Spots
- Treating dipstick results as diagnoses (not just pointers)
- Ordering investigations without a clear clinical question
- Failing to explain test rationale to patients in consultations
- Not having a safety net plan for results
- Interpreting mildly abnormal results in isolation (missing context)
- Not considering drug causes of abnormal results first
- Missing the emotional dimension of a results consultation
- Forgetting medication monitoring schedules (methotrexate, lithium, etc.)
Tutorial Ideas & Reflective Questions
Tutorial Scenarios:
- Review a set of blood results together — what story do they tell? What question was being asked?
- Role-play: deliver an abnormal result to a worried patient
- Case: patient with fatigue and a full screen — what to do with each result?
- Audit exercise: which investigations were ordered last week — were they all clearly indicated?
Reflective Questions:
- "What question were you trying to answer with that test?"
- "How would the result have changed your management?"
- "How did you explain the result to the patient?"
- "What would you do if the result comes back while you're on annual leave?"
- "What are the risks of over-testing in primary care?"
Section 18
🧩 Memory Aids & Cheat Sheets
Quick Reference — Key Thresholds to Know
| Test | Key Threshold | Meaning |
|---|---|---|
| HbA1c | ≥48 mmol/mol | Diabetes; 42–47 = pre-diabetes |
| eGFR | <60 mL/min | CKD (if persistent ≥3 months) |
| ACR | >3 mg/mmol | Microalbuminuria (clinically significant) |
| K+ | >6.5 mmol/L | Urgent action required |
| ABPM | ≥135/85 mmHg | Confirmed hypertension |
| QTc | >500 ms | High risk torsades — refer |
| ABPI | <0.8 | Significant arterial disease — no compression bandaging |
| FEV1/FVC | <0.70 | Obstructive pattern (COPD post-bronchodilator) |
| Calprotectin | <50 μg/g | IBD unlikely |
| CHADSVASC2 | ≥2 (men) ≥3 (women) | Anticoagulate for AF |
Section 19
❓ Frequently Asked Questions
What investigations should I do first for a patient presenting with unexplained fatigue?▶
Start with: FBC (anaemia, haematological cause), U&E (renal/electrolyte cause), LFTs (liver disease), TFTs (hypothyroidism is very common and treatable), fasting glucose or HbA1c (diabetes), ferritin (iron deficiency without anaemia), ESR/CRP (inflammatory cause). Consider coeliac screen (tTGA) if other symptoms suggest it. This combination covers the vast majority of treatable causes of fatigue in primary care.
Also consider:
- Vitamin D — deficiency is extremely common in the UK population and a frequently overlooked cause of fatigue, muscle weakness, and low mood. Check 25-OH vitamin D in anyone with unexplained fatigue, especially those with limited sun exposure, darker skin, or a predominantly indoor lifestyle.
- Testosterone (in males over 50) — low testosterone (hypogonadism) is an under-recognised cause of fatigue, low energy, reduced motivation, poor concentration, and low mood in men over 50. Request a morning serum total testosterone (ideally 8–10am, as levels are highest then). If low or borderline, repeat with LH and FSH to distinguish primary from secondary hypogonadism before referring or initiating treatment.
When should I refer a patient with abnormal LFTs?▶
Refer urgently if: signs of decompensated liver disease (jaundice, ascites, encephalopathy), very high transaminases (>10× upper limit of normal), or suspicion of hepatocellular carcinoma. For mildly elevated LFTs, first repeat after excluding reversible causes (alcohol, medications, fatty liver). If elevated and persistent after 6 weeks with no clear cause, refer for hepatology assessment.
A patient has a positive urine dipstick but no urinary symptoms. What do I do?▶
Do NOT treat. This is asymptomatic bacteriuria. Treating asymptomatic bacteriuria (except in pregnancy or before urological procedures) increases antibiotic resistance without improving outcomes. The exception: pregnant women with confirmed bacteriuria should be treated regardless of symptoms.
What comes up most in AKT on the topic of investigations?▶
Commonly tested: HbA1c thresholds, spirometry interpretation (FEV1/FVC), drug monitoring schedules (methotrexate, lithium, amiodarone, clozapine), ECG interpretation (AF, STEMI, LBBB, QTc prolongation), D-dimer interpretation (only useful in low pre-test probability), and when NOT to treat (e.g., asymptomatic bacteriuria, coeliac on gluten-free diet). Know your ABPM threshold for confirming hypertension.
What do IMGs find most challenging about investigations in UK GP?▶
UK-specific systems (e.g., NHS cervical screening programme, QRISK3 for CV risk, NHS diabetes prevention programme referral thresholds) are often unfamiliar to IMGs. Also, the UK culture of restraint in investigations — being criticised for over-testing — is less common in other healthcare systems where more extensive investigation is the norm. Finally, the emphasis in UK GP on communicating investigation rationale and results to patients (rather than simply ordering them) is a key difference.
Section 12
🔥 AKT High-Yield Tips
The numbers, thresholds, and traps that come up repeatedly. Memorise these and gain marks.
🔥 High-Yield Facts — Investigations in AKT
Diagnostic Thresholds
- HbA1c ≥48 mmol/mol = diabetes; 42–47 = pre-diabetes
- eGFR <60 mL/min/1.73m² for ≥3 months = CKD
- ABPM ≥135/85 mmHg = confirmed hypertension
- FEV1/FVC <0.70 post-bronchodilator = COPD diagnosis
- ACR ≥3 mg/mmol = microalbuminuria (significant in CKD)
- D-dimer: only useful when pre-test probability is LOW
- CRP >100 mg/L strongly suggests bacterial infection
Classic AKT Traps
- Treating asymptomatic bacteriuria (wrong — except in pregnancy)
- Diagnosing coeliac on tTGA while patient is on gluten-free diet (invalid)
- Using HbA1c to diagnose diabetes in haemoglobinopathy (invalid)
- Raised ALP + normal GGT → bone disease not liver
- False high K+ due to haemolysis — repeat before acting
- RBBB alone = often benign; new LBBB = treat as STEMI equivalent
- Raised PSA is NOT diagnostic of prostate cancer
First-Line Tests by Presentation
- Fatigue → FBC, U&E, TFTs, LFTs, glucose
- Weight loss (unintentional) → FBC, CRP, LFTs, Ca, glucose, TFTs, CXR
- Hypertension → U&E, eGFR, dipstick urine, ECG, fasting lipids
- Suspected COPD → post-bronchodilator spirometry
- Suspected DVT → Wells score first, then D-dimer (if low probability)
- Suspected coeliac → tTGA IgA (on gluten diet)
Monitoring Blood Tests
- Methotrexate → FBC, LFTs every 1–3 months (toxicity monitoring)
- Lithium → serum lithium, TFTs, U&E every 6 months
- Amiodarone → TFTs, LFTs, CXR every 6 months
- ACE inhibitor / ARB → U&E within 1–2 weeks of starting
- Clozapine → FBC weekly for 18 weeks (mandatory agranulocytosis monitoring)
- Statins → LFTs at baseline; routine monitoring not required if asymptomatic
The "next most appropriate investigation" format. The answer is nearly always: the test that is most specific to the clinical scenario, not the most comprehensive. Knowing why each test is first-line (not just that it is) is what separates a pass from a high score.
Section 24 — AKT High-Yield (Expanded)
🔥 AKT High-Yield — Investigations (Full Tables)
The thresholds, first-line tests, comparison traps, and single-best-answer patterns that come up over and over again. Memorise these tables.
Diagnostic Thresholds — Numbers You Must Know▶
| Condition | Test | Diagnostic Threshold | AKT Trap / Note |
|---|---|---|---|
| Diabetes (overt) | HbA1c | ≥48 mmol/mol | Asymptomatic: 2 readings needed. Symptomatic: 1 is sufficient. |
| Pre-diabetes (IGR) | HbA1c | 42–47 mmol/mol | Do not treat with metformin unless BMI >35 or rapidly deteriorating — refer to prevention programme. |
| Diabetes (fasting) | Fasting plasma glucose | ≥7.0 mmol/L | Two readings if asymptomatic. HbA1c preferred for diagnosis in most (not in haemoglobinopathy). |
| Pre-diabetes (IFG) | Fasting plasma glucose | 6.1–6.9 mmol/L | Impaired Fasting Glucose. Increased T2DM risk. Lifestyle advice. |
| Hypertension (confirmed) | ABPM daytime mean | ≥135/85 mmHg | Clinic BP ≥140/90 → ABPM to confirm. Clinic BP ≥180/120 → treat without ABPM if end-organ damage. |
| CKD | eGFR | <60 mL/min/1.73m² persisting ≥3 months | Single reading insufficient. Two readings ≥90 days apart required for CKD diagnosis. |
| CKD microalbuminuria | ACR | ≥3 mg/mmol | Use early morning urine sample. ACR >30 = macroalbuminuria. Persistent ACR >3 = CKD even if eGFR normal. |
| COPD (spirometry) | FEV1/FVC post-BD | <0.70 (<70%) | Post-bronchodilator essential for COPD diagnosis. Do not diagnose on CXR alone. |
| Obesity (BMI) | BMI | ≥30 kg/m² = obese; ≥25 = overweight | Lower thresholds for South Asian populations: ≥27.5 = obese, ≥23 = overweight risk. |
| Hypercalcaemia (symptomatic) | Corrected calcium | >2.6 mmol/L (significant); >3.0 = emergency | Always correct for albumin. Primary hyperparathyroidism most common in GP. Malignancy: most common cause of severe hypercalcaemia. |
| Gout — urate treatment target | Serum urate | <360 µmol/L (maintain on allopurinol) | Target <300 µmol/L if severe or tophi. Normal urate during acute attack does NOT exclude gout. |
| Hypothyroidism (treat) | TSH | >10 mU/L = treat if asymptomatic; consider treating 4–10 if symptomatic | Sub-clinical: TSH raised, fT4 normal. Overt: TSH raised + low fT4. TSH alone for monitoring on levothyroxine. |
| PE (risk stratify) | Wells PE score | Low: <2, Moderate: 2–6, High: >6 | Only use D-dimer in LOW probability. High probability → CT-PA directly. Bilateral leg veins scan or CT-PA for DVT. |
| Hyperkalaemia (urgent) | K⁺ | >6.5 mmol/L = emergency | Always exclude haemolysis first for values 5.5–6.4. ECG: peaked T waves → broad QRS → sine wave pattern. |
First-Line Tests by Presentation — "What Do You Order First?"▶
| Presentation | First-Line Tests | Why / AKT Logic |
|---|---|---|
| Unexplained fatigue | FBC, U&E, LFTs, TFTs, HbA1c or fasting glucose, ferritin, ESR/CRP | Covers most common treatable causes. Consider coeliac screen (tTGA) if GI symptoms or positive family history. |
| Unexplained weight loss | FBC, CRP, LFTs, calcium, HbA1c, TFTs, CXR, faecal calprotectin (if GI symptoms) | Screen for malignancy, diabetes, hyperthyroidism, inflammatory disease. Urgent 2WW referral if red flags. |
| New hypertension | U&E (renal cause?), eGFR, ACR, urine dipstick, lipids, HbA1c, ECG | Check for end-organ damage (kidneys, heart). Exclude secondary causes. ABPM to confirm diagnosis. |
| Suspected COPD | Post-bronchodilator spirometry | CXR (exclude other causes), FBC (polycythaemia). Spirometry is THE diagnostic test — not CXR, not history alone. |
| Suspected coeliac disease | IgA anti-tTGA (tissue transglutaminase antibody) | Patient MUST be on normal gluten-containing diet. Check total IgA — IgA deficiency causes false negative tTGA (use IgG-based test instead). |
| Suspected SLE | FBC (cytopenias), U&E, ANA (antinuclear antibodies), complement (C3/C4), dsDNA antibodies, urine dipstick (proteinuria) | ANA is sensitive but not specific. dsDNA is more specific for SLE. Complement low in active SLE (consumption). |
| Suspected giant cell arteritis | ESR, CRP, FBC, LFTs | ESR typically >50, often >100. Do NOT wait for results to start steroids if clinical suspicion is high — irreversible blindness is the risk. |
| Suspected DVT | Wells DVT score → if low: D-dimer → if positive: USS leg veins | Wells ≥2 = USS directly without D-dimer. D-dimer only useful in low probability. Negative D-dimer in low probability effectively rules out DVT. |
| Chest pain (possible ACS) | ECG, troponin (serial 0h + 3h) | GP: call 999. Serial troponin essential — single normal value insufficient. Rising troponin = ACS. |
| Polyuria / polydipsia | Fasting glucose or HbA1c, U&E, calcium, TFTs, urinalysis | Most common cause = diabetes. Also: hypercalcaemia, hypokalaemia, CKD, diabetes insipidus (rare). Urinalysis for glycosuria. |
| Jaundice | LFTs, FBC, GGT, bilirubin, USS abdomen | Determine: pre-hepatic (haemolysis), hepatic (hepatitis, liver disease), or post-hepatic (obstruction). Urgent if rapidly worsening. |
| Anaemia (first visit) | FBC with MCV, reticulocyte count, ferritin, B12, folate | MCV guides next steps. Microcytic → ferritin. Macrocytic → B12/folate, TFTs. Always find the CAUSE before treating. |
| Haematuria (microscopic confirmed) | MSU, FBC, U&E, ACR, BP, USS kidneys + bladder | Age ≥40 with unexplained haematuria → 2WW urology referral. Exclude UTI first. Check ACR for glomerular cause. |
| New cough >3 weeks (smoker or red flags) | CXR | AKT trap: jumping to CT chest or D-dimer before CXR. CXR is always first-line. If suspicious CXR → CT chest. No red flags + normal CXR → safety-net and review. |
| Suspected heart failure (breathlessness, oedema) | NT-proBNP (or BNP) → echo only if raised | AKT trap: ordering echo without natriuretic peptide where NICE recommends BNP first. NT-proBNP <125 pg/mL = heart failure unlikely. If raised → echo. Also: ECG, CXR, FBC, U&E, TFTs. |
| Suspected giant cell (temporal) arteritis | ESR, CRP — AND start prednisolone urgently | AKT trap: waiting for temporal artery biopsy before starting steroids. START steroids on clinical diagnosis — do NOT delay. Biopsy can follow within 1–2 weeks. Typical ESR >50, often >100. |
| New macrocytosis (raised MCV) | FBC with retics, B12, folate, LFTs, TFTs, alcohol history | AKT trap: jumping to bone marrow biopsy. Always exclude common causes first. Check medications (methotrexate, hydroxyurea, azathioprine). Normal MCV does not exclude B12+iron combined deficiency (they cancel out). |
| Asymptomatic raised LFTs (incidental) | Repeat LFTs in 3 months + viral hepatitis screen (HBsAg, HCV antibody), alcohol history, metabolic review (glucose, lipids, BMI) | AKT trap: over-scanning (USS/CT) before basic serology and lifestyle review. Most incidental raised LFTs = NAFLD, alcohol, or drugs. Repeat before acting. If persists >6 months → hepatology. |
| Dyspepsia, age <55, no alarm features | H. pylori test-and-treat (stool antigen or urea breath test), trial PPI | AKT trap: referring for OGD in low-risk patients without alarm features. NICE: test for H. pylori first. If positive → eradicate. OGD only for alarm features or failure of empirical treatment. |
| Suspected IBD (chronic diarrhoea, weight loss, PR bleeding) | FBC, CRP/ESR, coeliac screen (tTGA), faecal calprotectin | AKT trap: labelling as IBS without excluding IBD or coeliac. Faecal calprotectin <50 µg/g makes IBD unlikely. If raised → colonoscopy via secondary care. Always check coeliac serology alongside. |
| Suspected peripheral arterial disease (intermittent claudication) | ABPI (Ankle-Brachial Pressure Index) | AKT trap: ordering CT angiogram directly from primary care. ABPI is first-line — non-invasive, available in GP. ABPI <0.8 = significant PAD. Refer vascular if <0.5 or rest pain/ulceration. Also: lipids, HbA1c, FBC. |
| New palpitations | ECG (resting 12-lead) — then TFTs, FBC, U&E, glucose | AKT trap: jumping to 24-hour Holter before doing a resting ECG. ECG is always first. If ECG normal but symptoms continue → ambulatory monitoring. Check TFTs: thyrotoxicosis is a common reversible cause. |
| Possible TIA (resolved focal neurological deficit) | Same-day TIA clinic / acute stroke service referral + appropriate brain imaging | AKT trap: doing carotid Doppler first and delaying specialist review. NICE: urgent assessment within 24h. Do NOT delay for carotid Doppler in primary care. Brain imaging (MRI DWI preferred) determines ABCD2-based risk. |
AKT Comparison Traps — "Which Test Is Better Here?"▶
| Question Type | Common Distractor | Correct Answer | Why |
|---|---|---|---|
| Confirming HTN diagnosis | Clinic BP reading | ABPM (24-hour) or HBPM | NICE requires ABPM/HBPM to confirm HTN before treating (unless very high BP or end-organ damage) |
| Diagnosing COPD | CXR, peak flow | Post-bronchodilator spirometry (FEV1/FVC <0.7) | NICE COPD: diagnosis requires spirometry. CXR does not diagnose COPD. Peak flow not used for diagnosis. |
| Diagnosing hypothyroidism | Free T4 alone | TSH (sensitive first-line screen) | TSH is most sensitive — rises before fT4 falls in early hypothyroidism. Check fT4 only if TSH abnormal. |
| Monitoring thyroid treatment | Free T4 | TSH (for primary hypothyroidism on levothyroxine) | TSH normalisation is the monitoring target. Check fT4 only if suspecting non-compliance or central hypothyroidism. |
| Diagnosing suspected PE | D-dimer first in everyone | Wells PE score first; D-dimer only if low probability | D-dimer in high-probability patient is meaningless. CT-PA needed if Wells >4 or D-dimer positive. |
| Renal stones | Plain KUB X-ray | CT KUB (non-contrast) | CT KUB detects all stone types including urate stones (invisible on X-ray). 10× more sensitive than plain film. |
| Disc prolapse / cord compression | X-ray spine | MRI spine | X-ray shows bone, not disc or cord. MRI is gold standard for neural compression. Always MRI for cauda equina. |
| B12 deficiency in nitrous oxide user | Serum B12, active B12 | Plasma homocysteine or MMA (methylmalonic acid) | Active B12 is unreliable in N₂O users. MMA/homocysteine detect functional B12 deficiency accurately. |
| Ovarian cancer risk assessment | CA125 alone | CA125 + pelvic USS (both needed per NICE NG12) | CA125 alone is non-specific and non-sensitive for early ovarian cancer. Always combine with USS. |
| AKI vs CKD (new raised creatinine) | eGFR alone | Previous eGFR + clinical context | Without a baseline, a single eGFR cannot distinguish AKI from CKD. Always look at the trend. |
| Routine low back pain (no red flags) | X-ray or MRI to "reassure" or because pain has persisted | NO imaging in primary care | NICE specifically states that people with low back pain should NOT usually have imaging requested in non-specialist settings unless serious underlying pathology is suspected. Ordering imaging is the trap. |
| Suspicious skin lesion (possible melanoma) | Biopsy in primary care, or "watch and wait" approach | Urgent referral (2WW) | NICE: do NOT biopsy in primary care if melanoma diagnosis is uncertain. Refer urgently. Primary care biopsy when diagnosis is uncertain is a wrong answer and potentially dangerous delay. |
Drug Monitoring Schedules — AKT Favourite Topic▶
| Drug | Monitor | When / How Often | Action if Abnormal |
|---|---|---|---|
| Methotrexate | FBC, LFTs, U&E, creatinine | Baseline; every 1–2 weeks until stable; then every 1–3 months | LFTs >3× ULN or WCC/platelets falling → stop, discuss with specialist |
| Lithium | Serum lithium, TFTs, U&E, eGFR | Every 3–6 months when stable; after any illness causing dehydration | Lithium toxicity signs: tremor, diarrhoea, confusion → check level urgently. Therapeutic range 0.4–1.0 mmol/L |
| Amiodarone | TFTs (fT3, fT4, TSH), LFTs, CXR, PFTs | Baseline; every 6 months; after dose change | Both hypo- and hyperthyroidism possible. Pulmonary toxicity: new breathlessness → CXR + PFTs |
| ACE inhibitor / ARB | U&E, eGFR | 1–2 weeks after starting and after each dose increase; if unwell (vomiting/diarrhoea) | K⁺ >5.5 → review dose or drug. eGFR fall >25% → investigate cause; withhold if AKI features |
| Clozapine | FBC (neutrophil count) | Weekly for 18 weeks, then 2-weekly for 34 weeks, then monthly | Neutrophils <1.5 → amber. <1.0 → stop immediately (agranulocytosis). Not negotiable. |
| Azathioprine / mercaptopurine | FBC, LFTs, U&E | Every 1–3 months when stable | Falling WCC or rising LFTs → dose reduction or stop. Check TPMT before starting (enzyme deficiency → toxicity risk) |
| Statins | LFTs at baseline; CK if symptomatic | Baseline LFTs; no routine monitoring if asymptomatic | CK >4× ULN + myalgia → stop. LFTs >3× ULN → stop. Routine LFT monitoring NOT required in asymptomatic patients. |
| SGLT2 inhibitors (gliflozins) | eGFR, U&E | Before starting; 2–4 weeks after starting; annually | Do not start if eGFR <45 (most indications). Stop during acute illness (euglycaemic DKA risk). Monitor for genital thrush, UTIs, Fournier's gangrene (rare). |
| Warfarin | INR | Daily initially; then weekly; then monthly when stable | INR >5: reduce/hold. >8 or bleeding: urgent reversal. New drug interactions: check INR within 1 week of any change. |
| Carbimazole | FBC (WCC) | Baseline; if fever/sore throat develops → immediate FBC | Agranulocytosis (rare but serious). Advise patient: any fever or sore throat → stop drug, seek urgent medical review, FBC same day |
Section 13
🎯 SCA High-Yield Tips
In the SCA, investigations often appear as the reason for the consultation — explaining results, discussing what to order, or managing patient anxiety about tests.
✅ What Examiners Want to See
- Clear explanation of why you are ordering a test — not just naming it
- Explaining what the result means in plain language
- Checking the patient understands before moving on
- Eliciting ICE before delivering results — "How have you been getting on since we did those tests?"
- Safety-netting around results — what to do if new symptoms develop
- Clear follow-up plan — who reviews the result and when
- Acknowledging uncertainty without panicking the patient
⚠️ Common Mistakes That Cost Marks
- Ordering a battery of tests without explanation (scattergun approach)
- Delivering results as a list of numbers without translation
- Not checking what the patient already knows or expects
- Rushing past the patient's emotional reaction to a result
- Forgetting to explain the follow-up plan
- Not safety-netting — "come back if anything worries you" is not enough
- Using medical jargon without checking understanding
🎯 SCA Consultation Pearls — Investigations
Saying why you ordered the test, what you found, what it means, how the patient feels about it — and what happens next. That is the complete results consultation arc.
If a result raises a red flag (e.g., possible malignancy, urgent referral needed), say it clearly. Do not hedge so much that the patient cannot understand the urgency.
Mildly raised PSA, slightly elevated LFTs, or a first mildly abnormal dipstick in a well patient usually does not require urgent action. Calm the patient while explaining your structured plan.
A markedly abnormal result + serious symptoms (e.g., chest pain + new LBBB, haematuria + weight loss, unexplained very low Hb) — act decisively and explain why urgency is needed.
⭐ What Actually Gets You Marks in the SCA — Investigations & Results
🔥 The Things Nobody Tells You Until It's Too Late
In investigations consultations:
- Saying out loud why you are ordering each test is worth marks — it is communication, not just clinical knowledge
- Asking if the patient has any questions about having a test is often missed but specifically assessed
- If a patient asks "but could it be cancer?" — address it directly; do not dodge it. Acknowledging the fear scores marks even if the answer is "I don't think so, and here's why"
- Closing the loop explicitly ("I will call you personally if anything needs urgent attention") is a high-scoring behaviour that many candidates skip
In results consultations:
- The patient's emotional response to a result is a data point — if they look shocked or tearful, pause and acknowledge it before continuing
- Translating numbers into meaning is not optional — it is the core skill being tested
- "What does this mean for me day to day?" is a question patients have in their head even if they don't ask it out loud. Answer it proactively.
- If you are uncertain about the next step, say so honestly and explain the safety net — uncertainty handled well is a strength, not a weakness
Not explaining follow-up clearly. Examiners consistently report that candidates discuss the test or the result, then end the consultation without saying: who will review the result, when, and what happens if it is abnormal. Patients leave the consultation with a test pending and no safety net. This is both a mark-losing behaviour in the exam and a patient safety issue in real practice. Make it automatic: every test you order gets a follow-up plan spoken out loud.
Section 14
💬 Useful Consultation Phrases — Investigations
Read these once. Use them in clinic tomorrow. They are designed to sound human, not scripted.
This script structure is consistently rewarded in the SCA. Work through these five steps whenever ordering any investigation.
- 1Link to symptoms
"Because of the tiredness you've been describing..." / "Given the symptoms you mentioned..."
- 2State the purpose
"...I'd like to check for..." / "...this test will help us look at whether your thyroid is working properly..."
- 3Set expectation (what you hope to find)
"Most of the time this comes back normal, which would be reassuring..." / "This is mainly to rule out..."
- 4Explain outcome paths
"If it shows X, we would do Y." / "If everything is normal but you're still not better, I'd want to see you again."
- 5Safety-net BEFORE results come back
"If your symptoms worsen before the results are back, don't wait — please seek help sooner."
Section 25 — SCA Investigation Cases
🎭 SCA Cases — Investigations & Results
These are the types of investigation-related scenarios that appear in the SCA. For each one: what the examiner is looking for, the consultation structure, and the phrases that score marks.
🗣 Explaining Investigation Results to Patients
This is an SCA goldmine. Explaining results badly is one of the most common reasons candidates lose marks.
The Results Consultation Framework
- 1Recap the reason for the test
"When you came in last time, we were concerned about your tiredness. We did some blood tests to try to understand why."
- 2Deliver the result in plain language
"The tests show your iron levels are quite low — we call that iron deficiency anaemia." Avoid jargon. Translate numbers into meaning.
- 3Explain what it means
"This explains why you have been so tired. When iron levels are low, the blood cannot carry oxygen as efficiently as it should."
- 4Pause for the patient's reaction (ICE)
"How does that sound to you? Was that what you were expecting?" Do not rush past this step.
- 5Explain the plan
"What I'd like to do is..." — be specific. Give options if appropriate. Invite questions.
- 6Safety-net and follow-up
Tell the patient exactly how and when results will be reviewed. Give them a clear point of contact for concerns.
When explaining complex results, deliver one chunk of information at a time and check understanding before continuing. "Does that make sense so far? Do you have any questions before I explain what we're going to do about it?" This technique is examiners' gold — it shows patient-centred communication, not information dumping.
Case 1 — Explaining an Abnormal Blood Result (Raised PSA)▶
Scenario: Mr Ahmed, 62, attended a routine appointment. You ordered a PSA as part of a health check discussion 2 weeks ago. PSA has returned at 7.2 ng/mL (age-appropriate upper limit ~3.0). He has no urinary symptoms. He is attending for the result.
What the examiner is looking for:
- ICE before delivering the result
- Explaining the result in plain language (not "your PSA is elevated")
- Acknowledging the patient's likely anxiety without catastrophising
- Explaining what PSA is and its limitations (not diagnostic for cancer)
- Clear plan: 2WW referral + mpMRI prostate before biopsy
- Addressing the question "Does this mean I have cancer?" directly and honestly
- Safety-net and follow-up plan
High-scoring phrases:
Telling the patient "this could be cancer" without context. Not explaining what PSA is. Not having a clear plan (mpMRI before biopsy is now standard). Not acknowledging the anxiety. Rushing to close the consultation without checking understanding.
Case 2 — Targeted Investigation Reasoning (Fatigue Consultation)▶
Scenario: Mrs Patel, 45, presents with 3 months of tiredness, weight gain of 3kg, and feeling cold. She asks you to "do a full blood test to find out what's wrong." She is expecting a comprehensive screen.
What the examiner is looking for:
- Clinical reasoning aloud — connecting symptoms to likely diagnoses
- Targeted investigation based on clinical picture (not "full screen")
- Explaining which test you are ordering and why
- Not being dismissive of her request for comprehensive testing, but explaining your reasoning
- Focusing on TFTs as the most likely diagnosis (hypothyroidism strongly suggested by triad of symptoms)
- Safety-net: what to do if tests are normal but symptoms persist
High-scoring phrases:
Examiners specifically note candidates who explain their investigation rationale. Saying "I want to check your thyroid because your symptoms really fit with how underactive thyroid presents" scores more highly than saying "I'll do TFTs, FBC, U&E, LFTs, ferritin, glucose, lipids, and an ECG."
Case 3 — Explaining an ECG Finding (New AF)▶
Scenario: Mr Kowalski, 68, came in for palpitations. You did an ECG and it shows atrial fibrillation (heart rate 88, irregularly irregular). He has no prior history of AF. He is not acutely unwell. He looks worried.
What the examiner is looking for:
- Calm, clear explanation of what AF is in patient-friendly language
- Acknowledging patient anxiety before explaining
- Explaining what further tests are needed (TFTs, echo, BP, bloods)
- Discussing anticoagulation without being alarmist (mention stroke risk clearly but calmly)
- Clear follow-up plan — cardiology or GP-led rate/rhythm control
- Advising about driving if relevant (DVLA: 4 weeks off driving after new AF diagnosis — inform patient)
- Safety-netting: what to do if symptoms worsen
High-scoring phrases:
Case 4 — Declining an Unnecessary Investigation Request▶
Scenario: Mr Singh, 28, presents anxious about a family history of heart disease. He has read online about "full cardiac screening" and specifically requests a CT coronary angiogram, a full lipid profile, an ECG, and troponin. He is a non-smoker, healthy BMI, no symptoms. He is quite insistent.
What the examiner is looking for:
- Acknowledging and validating the patient's concern (not dismissing it)
- Explaining what investigations are genuinely useful and why
- Politely but clearly explaining why CT coronary angiogram is not appropriate at his age and risk level (radiation, incidental findings, false positives)
- Offering what IS appropriate: fasting lipids, BP, glucose, QRISK3 calculation, lifestyle advice
- Shared decision-making without being dismissive or authoritarian
- Maintaining the relationship even when declining the request
High-scoring phrases:
Examiners do not want to see candidates simply refusing patient requests. They want to see explanation, empathy, and an alternative. Declining a request without offering something constructive in its place is a fail indicator. Always say: "I'm not going to do X, but I am going to do Y, and here's why."
Case 5 — Breaking Concerning News About a Result (Possible Malignancy)▶
Scenario: Mrs Thompson, 54, came in 2 weeks ago with weight loss and fatigue. You ordered blood tests which showed a raised CA125 of 68 U/mL. You have arranged a pelvic USS which shows a complex ovarian mass. She is attending to discuss these results. She lives alone and came to the appointment alone.
What the examiner is looking for:
- Warning shot — prepare the patient before delivering concerning news
- Delivering the information clearly but compassionately
- Not using the word "cancer" without explanation — but not being evasive either
- Checking understanding and emotional state repeatedly
- Clear plan: urgent referral via 2WW pathway to gynaecology/oncology
- Acknowledging that she is alone and offering support
- Not overwhelming with information in one go
- Giving space for silence and emotional reaction
High-scoring phrases:
Before delivering potentially serious news, always give a warning shot: "I have the results back — and I do need to talk through something with you." This short preparation phrase reduces the shock response, improves information retention, and is specifically assessed in the SCA "Relating to Others" domain. Candidates who dive straight into abnormal results without preparation consistently lose marks here.
Case 6 — Explaining Drug Monitoring (Methotrexate)▶
Scenario: Mr Okafor, 41, has been on methotrexate 15mg weekly for psoriatic arthritis for 6 months. His latest monitoring bloods show ALT 78 U/L (upper limit of normal = 56). He did not know he was supposed to be having regular blood tests and has only had one previous check. He is not aware of any symptoms.
What the examiner is looking for:
- Explaining what methotrexate monitoring is and why it matters — without alarming the patient
- Explaining what the ALT result means (mildly raised liver enzyme)
- Appropriate clinical action: recheck in 2–4 weeks, consider dose adjustment or specialist review
- Not stopping the medication without discussion with the rheumatologist/dermatologist
- Addressing the system failure (patient not adequately informed) without blame
- Empowering the patient going forward — what to watch for, when to call
High-scoring phrases:
Case 7 — "I Want an MRI for My Back" (No Red Flags)▶
Scenario: Mr Bradley, 38, presents with 6 weeks of low back pain after lifting at work. No neurological symptoms, no bladder or bowel change, no night pain, no weight loss. He has read online about MRI being "the gold standard" and is requesting one. He seems frustrated that his previous GP only offered paracetamol.
What the examiner is looking for:
- Systematically and clearly checking for red flags (cauda equina, malignancy, infection, fracture, inflammatory) — say them out loud
- Explaining why MRI is not indicated for simple mechanical back pain without red flags
- Explaining the concept of "incidentalomas" — imaging can show findings that create more anxiety without changing management
- Validating his frustration without criticising the previous GP
- Offering what IS appropriate: analgesia review, active self-management, physiotherapy
- Specific red flag safety-net — naming the symptoms that would change the plan
High-scoring phrases:
Not checking red flags explicitly before declining the request. Declining the MRI without offering any alternative. Being dismissive of the patient's concerns. Not safety-netting clearly with the specific symptoms that warrant urgent review. Ordering the MRI "to reassure" — this is poor doctoring and examiners note it.
Explaining to the patient that spinal MRIs frequently reveal disc bulges and degenerative changes that are present in the majority of people over 30 — and often not causing symptoms — is a genuinely patient-centred explanation. It reframes the conversation from "you're refusing my test" to "I'm protecting you from unnecessary anxiety." Examiners value this level of clinical communication.
Case 8 — "I Want a CT to Rule Out Lung Cancer" (Smoker, 3-Week Cough)▶
Scenario: Mr Jones, 55, 30 pack-year smoker, presents with a dry cough for 3 weeks. No haemoptysis, no weight loss, no breathlessness at rest, no constitutional symptoms. He saw a news article about lung cancer and is very anxious. He is specifically requesting a CT chest to "rule it out." Normal examination.
What the examiner is looking for:
- Acknowledging the patient's anxiety — this is a reasonable concern in a 55-year-old smoker
- NOT dismissing concerns — offering something appropriate
- Explaining that CXR is the correct first-line investigation (not CT) and why
- Discussing the radiation dose and incidentaloma risk of low-threshold CT
- Clear plan: CXR arranged today + review of result + safety-net
- Addressing smoking cessation sensitively — not punitively
- Clear red flags the patient must return for
High-scoring phrases:
Examiners do not want a doctor who dismisses a worried smoker with a cough. They do not want a doctor who instantly agrees to CT either. The highest-scoring answer offers a genuinely useful first-line investigation (CXR), explains the clinical logic clearly, and maintains a warm, non-punitive conversation about smoking. Declining CT while arranging CXR shows clinical reasoning — not gatekeeping.
Case 9 — "I Want a Full Body Scan" (Health Anxiety)▶
Scenario: Mrs Chen, 42, presents requesting a "full body MRI scan to check everything is OK." She has no specific symptoms. She is clearly anxious, mentions her father died of cancer last year, and feels she "cannot relax" without knowing she is healthy. She has researched this extensively online and can name specific private clinics that offer it.
What the examiner is looking for:
- Exploring and acknowledging the emotional context — her father's death — before talking about investigations at all
- Understanding ICE: she is using investigation requests as a way of managing anxiety
- Explaining the real harms of indiscriminate imaging: radiation (CT), incidentalomas, the anxiety of borderline findings
- Not flatly refusing, but reframing: what ARE the appropriate checks for her age and risk?
- Addressing the health anxiety directly and compassionately — signposting psychological support if appropriate
- Offering a structured, targeted approach: relevant screening, specific symptom-led tests if anything is worrying her
High-scoring phrases:
This case tests whether the candidate recognises that the investigation request is a proxy for health anxiety and grief — not a straightforward clinical question. The candidate who addresses the emotional driver of the request and offers psychological support alongside targeted clinical checks will score highly in all three SCA domains. The candidate who simply declines "full body scan" and offers a blood test instead will miss the mark.
Whole-body imaging in asymptomatic people generates incidental findings in up to 40% of scans. Most are benign but require follow-up imaging, biopsies, and months of worry. This "cascade of investigation" is a recognised cause of patient harm that goes far beyond radiation exposure. Being able to explain this clearly and compassionately to a patient — rather than just saying "it's not indicated" — is a mark-winning clinical communication skill.
Case 10 — Weight Loss + Persistent Cough, Normal CXR Already Done▶
Scenario: Mr Harris, 62, 25 pack-year smoker, presents with 8 weeks of persistent dry cough and 5kg unintentional weight loss. His previous GP arranged a CXR 3 weeks ago which was reported as "normal." He is hoping this means everything is fine. On examination: mild finger clubbing. He asks if there is any point in any further tests.
What the examiner is looking for:
- Not over-reassuring the patient based on a normal CXR alone
- Understanding that CXR has limited sensitivity for early lung cancer — a normal CXR does not rule it out
- Identifying the red flag cluster: smoker + persistent cough + weight loss + clubbing
- Clear plan: urgent 2WW CT chest referral (NICE NG12 criteria)
- Explaining the next step clearly without catastrophising
- Acknowledging the patient's hope that the normal CXR is reassuring — without reinforcing a false sense of safety
High-scoring phrases:
This is a high-yield AKT and SCA scenario. A normal CXR does NOT exclude lung cancer — sensitivity is modest, particularly for early or hilar lesions. NICE NG12 and NHS England direct-access diagnostics guidance support CT chest in appropriate patients with red flag symptoms even when CXR is normal. Candidates who say "the X-ray is normal, so let's just watch and wait" are making a patient safety error.
Case 11 — Macrocytosis + Tingling in a Young Adult (Nitrous Oxide)▶
Scenario: Jasminder, 23, attends with 6 weeks of tingling in both hands and feet and occasional unsteadiness. Routine bloods from her previous GP show MCV 108 fL (macrocytosis). Serum B12 and folate both reported as "within normal limits." She is a university student, diet seems varied. She seems embarrassed and vague about her lifestyle.
What the examiner is looking for:
- Recognising that normal serum B12 does NOT exclude functional B12 deficiency from nitrous oxide
- Asking specifically about "balloons," "whippits," or "laughing gas" — sensitively and non-judgementally
- Understanding that MMA or plasma homocysteine are the appropriate tests in this clinical context
- Recognising the urgency — neurological features (tingling + unsteadiness) require prompt action
- Explaining the investigation rationale to the patient without shaming her
- Not waiting for further results before acting if neurological signs progress
High-scoring phrases:
The combination of macrocytosis + normal B12 + neurological symptoms in a young person is a classic presentation of nitrous oxide-related functional B12 deficiency. NICE guidance explicitly states: do NOT rely on total or active B12 alone; use MMA or homocysteine. Candidates who order a "repeat B12" or say "B12 is normal so it's not a B12 problem" fail this case at both the knowledge and the communication level.
Subacute combined degeneration of the spinal cord can be irreversible. If the patient has ataxia, positive Romberg, or spastic paraparesis — do not wait for MMA results. Start parenteral hydroxocobalamin immediately and arrange urgent neurology input. The risk of waiting outweighs any diagnostic gain.
Case 12 — Visible Haematuria After a Treated UTI▶
Scenario: Mrs Chen, 67, was treated for a UTI 4 weeks ago with a 3-day course of trimethoprim. The MSU confirmed E. coli, sensitive to trimethoprim. She returns today because she has noticed blood in her urine again. She has no further dysuria or frequency. She is otherwise well, no weight loss. She assumes the original UTI has come back.
What the examiner is looking for:
- Recognising that haematuria persisting after successful treatment of UTI is NOT simply a recurrent UTI
- Understanding NICE NG12: visible haematuria in a patient aged ≥45 warrants urgent suspected cancer pathway referral even after UTI treatment
- Not falsely reassuring the patient that this is "just another UTI"
- Explaining the rationale for referral clearly — without alarming the patient unduly
- Appropriate safety-net if referral is delayed
High-scoring phrases:
NICE NG12 (Suspected Cancer Recognition and Referral): offer urgent suspected cancer pathway referral for urological cancer in patients aged ≥45 with unexplained visible haematuria that is NOT associated with UTI, OR visible haematuria that persists or recurs after treatment of UTI. Do NOT simply repeat the MSU and retreat. The "just another UTI" assumption in a 67-year-old with post-treatment haematuria is a patient safety failure.
The patient has a ready-made explanation — "the UTI came back" — and will be pushing for that framing. The clinical skill is redirecting gently but clearly. You must not collude with the patient's preferred (but incorrect) explanation. Examiners specifically look for the candidate's ability to hold a clinical position under social pressure without being dismissive or dismissing the patient's concerns.
Section 20