High-Yield Endocrinology for MRCP Part 1

TL;DR

Endocrinology in MRCP Part 1 rewards logical thinking over memorisation. This guide summarises high-yield endocrinology for MRCP Part 1, covering the five most-tested subtopics, common traps, a mini-case, and a practical study checklist to build exam-ready clarity and speed.

Why Endocrinology Matters in MRCP Part 1

Endocrine disorders feature prominently across the Clinical Sciences section of MRCP Part 1. Questions rarely ask for definitions—they test reasoning through biochemical patterns, feedback loops, and differential diagnosis. Understanding why cortisol, TSH, or calcium shifts in a given case is the key to scoring higher.

According to the MRCP(UK) Part 1 content outline, endocrinology overlaps with metabolism, renal medicine, and neurology, often through clinical vignettes. Candidates confident in hormone pathways perform better in mixed-system questions and time-pressured scenarios.

The Five Most-Tested Endocrine Subtopics

1. Pituitary–Hypothalamic Axis

• Know dynamic tests: insulin tolerance, short Synacthen, and dexamethasone suppression.

• Identify patterns:

  • Cushing’s disease → ACTH high, cortisol suppresses only with high-dose dexamethasone.

  • Ectopic ACTH → ACTH high, no suppression at any dose.

  • Exogenous steroids → ACTH low, cortisol low-normal.

2. Thyroid Disorders

• Recognise TFT patterns:

  • Primary hypothyroidism: ↑TSH, ↓T₄

  • Secondary hypothyroidism: ↓TSH, ↓T₄

  • Subclinical: ↑TSH, normal T₄

• Common questions cover autoimmune markers (anti-TPO, anti-TSH receptor) and effects of drugs such as amiodarone and lithium.

3. Adrenal Disorders

• Addison’s disease (primary insufficiency): low cortisol, high ACTH, hyperpigmentation, hyponatraemia, hyperkalaemia.

• Secondary insufficiency: both cortisol and ACTH low, no pigmentation.

• Conn’s syndrome (primary hyperaldosteronism): hypertension, hypokalaemia, metabolic alkalosis.

• Always differentiate from Cushing’s by aldosterone and renin levels.

4. Calcium & Bone Metabolism

• Distinguish causes of hypercalcaemia:

  • Primary hyperparathyroidism: ↑Ca, ↑PTH, ↓PO₄

  • Malignancy: ↑Ca, ↓PTH, ↑PTHrP

• Vitamin D deficiency → low Ca, low PO₄, high ALP.

• Osteomalacia and osteoporosis differ by phosphate and ALP patterns.

5. Diabetes & Metabolic Syndromes

• Understand insulin physiology and counter-regulatory hormones.

• Know diagnostic thresholds (fasting glucose ≥ 7 mmol/L; HbA1c ≥ 48 mmol/mol).

• MRCP-favourite differentials: DKA vs HHS, and side-effects of diabetes drugs (e.g. SGLT2 inhibitors → euglycaemic ketoacidosis).

• Lipid disorders (familial hypercholesterolaemia) and xanthomata frequently appear in mixed-system stems.

  
  

Quick Reference Table – Hormonal Pattern Recognition

Disorder	Serum Na⁺	Serum K⁺	Cortisol	ACTH	Key Clue
Addison’s disease	↓	↑	↓	↑	Hyperpigmentation
Secondary adrenal insufficiency	↓/N	N	↓	↓	No pigmentation
Conn’s syndrome	N/↑	↓	↑Aldo	↓Renin	Resistant hypertension
SIADH	↓	N	N	N	Euvolaemic hyponatraemia
Diabetes insipidus	↑	N	N	N	Polyuria, dilute urine

Mini-Case Example

Question: A 32-year-old woman has fatigue, weight loss, and darkening of her palms. BP = 88/54 mmHg.Na⁺ = 126 mmol/L, K⁺ = 6.1 mmol/L, cortisol = 60 nmol/L, ACTH = 160 pg/mL.

Diagnosis: Primary adrenal insufficiency (Addison’s disease).

Explanation: Low cortisol with elevated ACTH and pigmentation indicates primary adrenal failure. Mineralocorticoid loss explains the hyponatraemia and hyperkalaemia. Confirm with a short Synacthen test and screen for autoimmune causes.

Practical Study-Tip Checklist

1. Master feedback loops. Use flowcharts to trace hypothalamus → pituitary → end organ.

2. Practise dynamic test logic. Convert results into “↑ or ↓” grids for quick recall.

3. Use spaced repetition. Review endocrine patterns 24 h and 72 h after first study.

4. Integrate mocks. Take one timed paper weekly—try a Crack Medicine mock test.

5. Leverage analytics. Identify weak topics using the performance dashboard in the Crack Medicine QBank.

6. Cross-link systems. Relate endocrine findings to renal and metabolic questions to maximise retention.

   
   

Common Traps in MRCP Part 1 Endocrinology

• Mixing SIADH with Addison’s hyponatraemia → potassium is normal in SIADH, high in Addison’s.

• Ignoring drug-induced thyroid changes (amiodarone, lithium, interferon).

• Forgetting unit conversions (μg → nmol).

• Overlooking MEN syndromes – associate genes MEN1, RET.

• Neglecting osteoporosis differentials – raised ALP in osteomalacia, normal in primary osteoporosis.

  
  

FAQs

1. How much endocrinology appears in MRCP Part 1?Around 10–15 % of Paper 1, with overlap in metabolism and renal systems.

2. Are dynamic tests frequently tested?

Yes—Synacthen, dexamethasone suppression, OGTT, and water-deprivation tests appear regularly.

3. Which book should I use for endocrine prep?

Oxford Handbook of Clinical Medicine (11 ed.) and Davidson’s Principles & Practice of Medicine (24 ed.) cover the essentials concisely.

4. How can I practise endocrinology questions for free?

Use Free MRCP MCQs and try limited mock tests on Crack Medicine before subscribing.

5. How can I integrate endocrinology into my wider study plan?

Refer to the MRCP Part 1 overview and pair endocrine blocks with metabolic and renal topics for better conceptual overlap.

Ready to start?

Endocrinology rewards logic, not memorisation. Structure your prep with spaced revision, clinical cases, and regular mocks. Start practising today through the Crack Medicine QBank, attempt a mock test, and explore comprehensive lectures for deeper understanding. See the full MRCP Part 1 overview to connect this module with your overall revision path.

Sources

• MRCP(UK) Part 1 Exam Content Outline

• NICE CKS: Adrenal insufficiency

• NICE CKS: Thyroid disorders

• Oxford Handbook of Clinical Medicine, 11th Ed.

• Davidson’s Principles and Practice of Medicine, 24th Ed.