Endocrinology: HPA axis suppression: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Endocrinology: HPA axis suppression

Sample item

A 50-year-old man who has taken prednisolone daily for eight months stops it abruptly and develops hypotension, vomiting and hypoglycaemia. Which change in the axis explains this?

ALoss of renin secretion causing aldosterone deficiencyBRebound ACTH excess causing adrenal exhaustionCProlonged suppression of CRH and ACTH has caused atrophy of the zona fasciculataDAutoimmune destruction of the whole adrenal cortex

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Prolonged suppression of CRH and ACTH has caused atrophy of the zona fasciculata

Exogenous glucocorticoid exerts negative feedback on the hypothalamus and pituitary, so CRH and ACTH fall and the zona fasciculata and reticularis atrophy. After abrupt withdrawal the gland cannot make cortisol, causing adrenal insufficiency. The zona glomerulosa is spared because angiotensin II and potassium control it.

Option by option

A. Loss of renin secretion causing aldosterone deficiency
Renin secretion is not lost, and aldosterone is preserved in secondary adrenal failure.
B. Rebound ACTH excess causing adrenal exhaustion
ACTH is suppressed by prolonged steroid therapy, so it is not in excess.
C. Prolonged suppression of CRH and ACTH has caused atrophy of the zona fasciculata (correct)
Correct. Feedback suppression of CRH and ACTH leaves an atrophied cortex unable to make cortisol on withdrawal.
D. Autoimmune destruction of the whole adrenal cortex
Autoimmune adrenalitis is a different cause and is not due to prednisolone withdrawal.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is C, Prolonged suppression of CRH and ACTH has caused atrophy of the zona fasciculata. Exogenous glucocorticoid exerts negative feedback on the hypothalamus and pituitary, so CRH and ACTH fall and the zona fasciculata and reticularis atrophy.

Why is "Loss of renin secretion causing aldosterone deficiency" not the answer?

Renin secretion is not lost, and aldosterone is preserved in secondary adrenal failure.

Why is "Rebound ACTH excess causing adrenal exhaustion" not the answer?

ACTH is suppressed by prolonged steroid therapy, so it is not in excess.

Why is "Autoimmune destruction of the whole adrenal cortex" not the answer?

Autoimmune adrenalitis is a different cause and is not due to prednisolone withdrawal.

What concept does this question test?

It tests Endocrinology: HPA axis suppression in Physiology. After abrupt withdrawal the gland cannot make cortisol, causing adrenal insufficiency. The zona glomerulosa is spared because angiotensin II and potassium control it.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Endocrinology: HPA axis suppression?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.