Drug of Choice Cheatsheet — Endocrinology Focus (MRCP Part 1)

Crack Medicine
Oct 19
4 min read

TL;DR This cheatsheet summarises the drug of choice in key endocrine conditions for MRCP Part 1 revision. You’ll get a quick list, a mini-case to test recall, and a practical study checklist for retention.

Why this matters (and exam scope)

Pharmacology questions in the endocrinology & metabolic medicine domain can be deceptively tricky: the “correct” drug often depends on patient subgroups (pregnancy, renal failure, acute vs chronic) or disease stage (emergency vs maintenance). Since MRCP Part 1 typically allocates ~14 questions to endocrinology/diabetes/metabolic medicine (out of 200) thefederation.uk +2StudyMRCP+2, knowing first-line therapies and common traps can salvage marks in tight papers.

The MRCP Part 1 exam is delivered as two three-hour papers of 100 best-of-five MCQs each thefederation.uk +1. There is no negative marking. Your aim is to pick the single best answer from plausible alternatives.

In endocrine pharmacology, the “drug of choice” concept almost always means initial definitive therapy, not rescue therapy or adjuncts — unless the question specifies an emergency setting.

Below are eight high-yield endocrine conditions, their first-choice drugs, and key caveats.

Key Drug-of-Choice Listings & Caveats

Condition	Drug of Choice	Key Notes / Exceptions
Primary (overt) hypothyroidism	Levothyroxine (T₄)	Standard replacement; in patients with undiagnosed adrenal insufficiency, give glucocorticoid cover first.
Graves’ thyrotoxicosis (non-pregnant)	Carbimazole	Carbimazole is preferred except in first trimester pregnancy.
First trimester hyperthyroidism	Propylthiouracil (PTU)	PTU is safer in early pregnancy; switch to carbimazole after first trimester if needed.
Thyroid storm	PTU + propranolol + hydrocortisone + potassium iodide (after PTU)	Multimodal control: block synthesis, block conversion, suppress release.
Primary hyperaldosteronism	Spironolactone or eplerenone	Spironolactone preferred; eplerenone more selective if gynecomastia concerns.
Adrenal (Addisonian) failure	Hydrocortisone + fludrocortisone	Glucocorticoid + mineralocorticoid replacement.
Acromegaly (pre-surgery / adjunct)	Octreotide (somatostatin analogue)	Reduces GH secretion; may be used before or after surgery.
Hyperprolactinaemia	Cabergoline (preferred) or bromocriptine	Cabergoline is better tolerated and more effective long term.
Type 2 diabetes (first line)	Metformin	Unless contraindications (renal/hepatic failure, contrast risk).
Diabetic ketoacidosis (DKA)	IV regular insulin + fluids + K⁺ correction	Standard protocol in metabolic emergencies.

You may also encounter endocrine emergencies such as adrenal crisis (hydrocortisone IV) or severe hypercalcaemia (bisphosphonates + hydration), but those are less frequently labelled as “drug of choice” in MRCP.

Mini-Case / MCQ (with explanation)

A 32-year-old woman presents in her 9th week of pregnancy with signs of hyperthyroidism (palpitations, tremors). You confirm suppressed TSH and elevated free T₄. What is the best initial antithyroid drug in this scenario? A. CarbimazoleB. PropylthiouracilC. MethimazoleD. Radioactive iodine ablationE. Beta-blocker only

Answer: B. Propylthiouracil Explanation: In the first trimester, PTU is preferred to carbimazole due to lower teratogenic risks (e.g. agranulocytosis, skin defects). After the first trimester, many clinicians switch to carbimazole to reduce hepatic risks of PTU. (Note: radioactive iodine is contraindicated, and beta-blockers are adjuncts, not definitive therapy.)

This question exemplifies a classic “pregnancy exception” trap.

Flat-lay of MRCP Part 1 study setup with endocrine pharmacology notes and QBank practice on laptop.

Study Checklist & Retention Tips

Organise by gland/system (thyroid, adrenal, pituitary, metabolic) so you can batch recall similar drug classes.
Use flashcards with mechanism + side effect to reinforce linkages (e.g. spironolactone → antiandrogen effects).
Do timed MCQ blocks in the past two weeks focusing only on endocrine pharmacology.
After each block, error-tag those you missed, revisit mechanism logic, and re-test later.
Combine spaced repetition + frequent review (weekly mini-reviews).
Use a QBank platform (e.g. Pastest, BMJ On Examination) in timed mode to simulate exam conditions.
Translate memorised lists into clinical vignettes — ask yourself: “If pregnant, if renal failure, if emergency?” to force nuance.

Common Pitfalls & Traps (5)

Assuming carbimazole is always safe in pregnancy. In first trimester, PTU is the safer option.
Overusing high-dose insulin in DKA without checking K⁺ levels — you can precipitate hypokalaemia.
Confusing adrenal crisis treatment with maintenance therapy. Maintenance = hydrocortisone + fludrocortisone; crisis = high-dose hydrocortisone IV.
Choosing metformin in severe renal impairment — contraindicated or unsafe.
Ignoring adjunctive meds (e.g. beta-blockers in thyrotoxicosis); selecting them as “drug of choice” when they are only supportive.

FAQs

Q1. Does MRCP Part 1 frequently test endocrine drug-of-choice questions?

Yes — approximately 10–15% of pharmacology and endocrine questions demand correct first-line drug selection in endocrine settings.

Q2. Do I need to memorise doses?

No. For MRCP Part 1, it’s far more important to know which drug and why. Dose specifics are rarely tested.

Q3. Can combination therapy ever be the “drug of choice”?

Only in emergencies (e.g. thyroid storm). Otherwise, the exam generally expects a single best initial therapy.

Q4. Where can I practise relevant MCQs?

Use reputable QBank platforms such as Pastest or BMJ On Examination, focusing on endocrine / endocrine pharmacology modules.

Q5. Is switching between drugs (e.g. PTU to carbimazole) often tested?

Yes — especially in special circumstances like pregnancy or side-effect risk. Be alert for stem clues.

Ready to start?

This endocrinology drug-of-choice cheatsheet gives you a high-yield reference you can return to in your final review. Use it as a scaffold; challenge yourself using MCQs, error correction and timed practice. Pairing this with QBank practice and a mock simulation in the final weeks will solidify your recall.

If you wish to expand into other systems, check out our wider MRCP Part 1 overview, or practise related MCQ banks. With repeated exposure and clinical logic, you’ll move from memorisation to confident selection on exam day.