Endocrinology and metabolic medicine accounts for roughly 25 questions across the two MRCP Part 1 papers — consistently one of the three highest-yield specialties.
Yet it is where well-prepared candidates haemorrhage marks, because endocrine questions reward precise recall of numbers and mechanisms over clinical gestalt.
Endocrinology tests whether you understand feedback loops or have simply memorised disease names. The questions are pattern-rich and number-heavy: a single sodium value, a suppressed TSH, a paradoxical cortisol response.
Get comfortable with the axes and the thresholds, and this becomes one of the most reliable scoring sections on the paper.
Why Endocrinology Matters for MRCP Part 1
Endocrinology rewards a small, finite body of knowledge applied repeatedly. Unlike infectious diseases, the syllabus is bounded — the hypothalamic-pituitary-adrenal, thyroid and gonadal axes, calcium homeostasis, and diabetes account for most stems.
Because the same dynamic tests (short Synacthen, oral glucose tolerance, dexamethasone suppression, water deprivation) recur year after year, a candidate who genuinely understands the physiology can reason through unfamiliar stems rather than relying on memory alone.
The metabolic component — porphyrias, inborn errors, lipid disorders and electrolyte derangements — is smaller but disproportionately discriminating. These questions separate candidates who pass comfortably from those who scrape through. Investing here pays.
For IMGs: If you trained outside the UK, you may have used different reference ranges and assay conventions. MRCP uses UK laboratory norms and SI units throughout — calcium in mmol/L, glucose in mmol/L, not mg/dL. Drill the UK thresholds (corrected calcium, HbA1c in mmol/mol as well as %, TSH ranges) until they are automatic. A correct mechanism with the wrong unit still loses the mark.
High-Yield Endocrinology Topics
Thyroid Disease
The thyroid axis is the single most heavily examined endocrine topic. You must interpret a TSH and free T4 pair instantly and reason backwards to the lesion.
- Graves’ disease — diffuse goitre, ophthalmopathy, pretibial myxoedema, thyroid acropachy. TSH-receptor antibodies positive; uniform uptake on isotope scan.
- Toxic multinodular goitre / toxic adenoma — older patients, no eye signs, focal or patchy uptake on scan. Important contrast to Graves’.
- De Quervain’s (subacute) thyroiditis — painful goitre, raised inflammatory markers, low isotope uptake, post-viral. Self-limiting; treat with NSAIDs/steroids, not antithyroid drugs.
- Sick euthyroid syndrome — low T3 (and later T4) with inappropriately normal/low TSH in acute illness. Do not treat; recheck on recovery.
- Amiodarone — causes both hypothyroidism (Wolff-Chaikoff) and two types of thyrotoxicosis (type 1 iodine-load, type 2 destructive thyroiditis). A recurring stem.
Consultant tip: A suppressed TSH with low uptake on isotope scan means the gland is not overproducing — think thyroiditis or exogenous thyroxine, never Graves’. This single discriminator answers a remarkable number of thyroid stems.
Adrenal Disorders
The adrenal axis tests your command of dynamic testing. Know which test confirms, which excludes, and what the paradoxical results mean.
- Addison’s disease — hyperpigmentation, hyponatraemia with hyperkalaemia, postural hypotension. Confirmed by failed cortisol rise on short Synacthen test.
- Cushing’s syndrome — fails to suppress on low-dose dexamethasone. High-dose suppression and ACTH then localise: pituitary (Cushing’s disease) suppresses, ectopic ACTH and adrenal tumours do not.
- Conn’s syndrome (primary hyperaldosteronism) — hypertension with hypokalaemia and a suppressed renin:raised aldosterone ratio.
- Phaeochromocytoma — episodic headache, sweating, palpitations; associated with MEN 2, von Hippel-Lindau, neurofibromatosis. Alpha-block before beta-block.
- Congenital adrenal hyperplasia (21-hydroxylase deficiency) — raised 17-hydroxyprogesterone; virilisation with salt-wasting.
Pituitary and Hypothalamic Disease
- Acromegaly — diagnosed by failure of GH to suppress on oral glucose tolerance test; IGF-1 for screening and monitoring.
- Prolactinoma — galactorrhoea, amenorrhoea, bitemporal hemianopia. First-line treatment is a dopamine agonist (cabergoline), not surgery.
- Diabetes insipidus — polyuria with dilute urine; water deprivation test distinguishes cranial (responds to desmopressin) from nephrogenic (does not).
- SIADH — euvolaemic hyponatraemia, low plasma osmolality, inappropriately concentrated urine, urinary sodium > 20 mmol/L.
- Hypopituitarism / Sheehan’s syndrome — postpartum pituitary infarction; failure of lactation and amenorrhoea are early clues.
For IMGs: MEN syndromes are a classic UK exam favourite. Commit them to memory: MEN 1 (parathyroid, pancreas, pituitary — the “3 Ps”), MEN 2a (medullary thyroid, phaeochromocytoma, parathyroid), MEN 2b (medullary thyroid, phaeochromocytoma, mucosal neuromas, Marfanoid habitus). These appear in both endocrinology and genetics stems.
Diabetes and Metabolic Medicine
- Diagnostic thresholds — fasting glucose ≥ 7.0 mmol/L, random/2-hour OGTT ≥ 11.1 mmol/L, or HbA1c ≥ 48 mmol/mol (6.5%).
- DKA — ketonaemia, glucose typically > 11 mmol/L, pH < 7.3 or bicarbonate < 15 mmol/L. Fixed-rate insulin and fluids; watch potassium.
- HHS — marked hyperglycaemia, hyperosmolality, minimal ketosis; older type 2 patients. Higher thrombotic risk.
- MODY — young, non-obese, strong autosomal dominant family history; sulphonylurea-responsive in HNF1A subtype.
- Lipids — familial hypercholesterolaemia (tendon xanthomata, autosomal dominant); the porphyrias and inborn errors round out the metabolic component.
Endocrinology Facts Worth Memorising
| Topic | Must-Know Fact |
|---|---|
| Acromegaly | GH fails to suppress on oral glucose tolerance test |
| Addison’s | Short Synacthen test confirms; Na low, K high |
| Cushing’s disease | Suppresses on high-dose dexamethasone (ectopic ACTH does not) |
| Conn’s syndrome | Raised aldosterone:renin ratio with hypokalaemic hypertension |
| SIADH | Euvolaemic hyponatraemia, urine Na > 20, concentrated urine |
| Diabetes insipidus | Water deprivation test; desmopressin separates cranial from nephrogenic |
| De Quervain’s thyroiditis | Painful goitre, low isotope uptake, raised ESR |
| Phaeochromocytoma | Alpha-blockade before beta-blockade — always |
| MEN 1 | Parathyroid, pancreas, pituitary (the 3 Ps) |
| HbA1c diagnostic | ≥ 48 mmol/mol (6.5%) confirms diabetes |
How to Approach Endocrinology Questions
- Locate the axis first. Before anything else, decide which hormonal axis the stem concerns — thyroid, adrenal, pituitary, calcium or glucose. This frames every subsequent decision.
- Read the paired hormones together. A hormone value is meaningless alone. A high free T4 with suppressed TSH is primary thyrotoxicosis; a high T4 with normal/raised TSH points to a TSH-secreting tumour or assay artefact. Always interpret the controller and the target together.
- Identify the dynamic test. Suppression tests (dexamethasone, OGTT) confirm excess; stimulation tests (Synacthen, water deprivation) confirm deficiency. Knowing the direction tells you what a “normal” or “paradoxical” result means.
- Anchor on the threshold. Endocrine stems hinge on numbers — corrected calcium, HbA1c, glucose, sodium. Commit the diagnostic cut-offs to memory and apply them coldly.
- Check for the syndrome. Scan for the association — MEN, autoimmune polyendocrine syndrome, von Hippel-Lindau. The buried clue (a family history, a second tumour) is often the answer.
Target: Aim to answer every thyroid and adrenal stem in under 60 seconds by drilling the TSH/T4 matrix and the suppression-versus-stimulation logic until it is reflexive. That speed banks time for the harder metabolic questions later in the paper.
Try MRCP Part 1 Free
Start a free 2-day trial — 30 exam-style questions plus sample videos, flashcards and Knowledge Library articles. A taste of our full 6,000+ question bank across all 17 specialties. No card, ends automatically.
Keep full access from £25 — when your trial ends it expires on its own, nothing to cancel.
Common Mistakes to Avoid
- Treating sick euthyroid syndrome. Abnormal thyroid function in an acutely unwell patient usually needs no treatment — just a repeat once recovered.
- Giving beta-blockers first in phaeochromocytoma. Unopposed alpha stimulation precipitates a hypertensive crisis. Alpha-blockade always comes first.
- Confusing the dexamethasone suppression results. Failure to suppress on low-dose confirms Cushing’s; the high-dose test and ACTH then localise the source. Candidates routinely muddle the two steps.
- Forgetting to correct calcium for albumin. Uncorrected calcium gives the wrong answer in hypoalbuminaemic patients — a deliberate trap.
- Ignoring the volume status in hyponatraemia. SIADH is a diagnosis of euvolaemia. Hypovolaemic or hypervolaemic hyponatraemia has a different cause and different management entirely.
Conclusion
Endocrinology is one of the most learnable, most predictable sections of MRCP Part 1. The physiology is finite, the dynamic tests recur, and the thresholds are fixed.
Candidates who treat it as rote memorisation struggle; those who understand the feedback loops can reason through any stem the Federation invents. Put your hours here early — the return on investment is among the highest of any specialty on the paper.
Practise with questions written to the current 2026 syllabus and reviewed by practising consultants — Revision Pro’s bank of 6,000+ MCQs covers every endocrine axis with detailed teaching explanations. For the bigger picture, see our complete MRCP Part 1 guide and the syllabus weightage breakdown to plan how much time endocrinology truly deserves in your revision schedule.
