skip to main content

Hypophysitis Multi-axis — SCE Medical Oncology MCQ

Instant feedback + full explanation. One question, done properly.

HardLung CancerHypophysitis Multi-axisSCE Medical Oncology

A patient on pembrolizumab presents with postural hypotension, hyponatraemia and hyperkalaemia. Morning cortisol is very low, ACTH and renin are high, and aldosterone is low. Pituitary MRI and the remaining anterior-pituitary profile are normal; adrenal CT shows no masses and 21-hydroxylase antibodies are positive. Which immune endocrinopathy best explains the pattern?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Primary adrenalitis causing mineralocorticoid and glucocorticoid failure

Low cortisol and aldosterone with high ACTH and renin localise to primary adrenal failure; positive 21-hydroxylase antibodies and normal adrenal CT favour immune primary adrenalitis in this pembrolizumab-treated patient. Anterior hypophysitis causing secondary glucocorticoid and mineralocorticoid failure: secondary adrenal failure has low or inappropriately normal ACTH and usually preserves aldosterone. Isolated ACTH deficiency causing secondary glucocorticoid and mineralocorticoid failure: isolated ACTH loss likewise preserves mineralocorticoid function. Bilateral adrenal metastases causing primary adrenal insufficiency: metastases could produce the same primary biochemical pattern, but the absence of adrenal masses and positive 21-hydroxylase antibodies distinguish autoimmune adrenalitis. Immune thyroiditis causing combined glucocorticoid and mineralocorticoid failure: thyroiditis does not explain the cortisol, ACTH, renin and aldosterone pattern.

Reference: Endocrine Society guideline for diagnosis and treatment of primary adrenal insufficiency (Published February 2016; current diagnostic framework): https://pubmed.ncbi.nlm.nih.gov/26760044/; KEYTRUDA 25 mg/mL UK summary of product characteristics (Current UK SmPC, updated June 2026): https://www.medicines.org.uk/emc/product/2498/smpc