Endocrinology: secondary adrenal insufficiency: 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: secondary adrenal insufficiency

Sample item

A woman 6 months after pituitary surgery has fatigue, hypotension and a low morning cortisol with low ACTH. Her serum potassium is normal. Why is potassium handling preserved?

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

The answer and the reasoning

A. Aldosterone is driven mainly by angiotensin II, not ACTH

In secondary adrenal failure ACTH is low, so cortisol falls, but the zona glomerulosa is controlled chiefly by angiotensin II and potassium, so aldosterone is preserved. Low ACTH also means no excess POMC-derived peptide, so there is no skin darkening.

Option by option

  • A. Aldosterone is driven mainly by angiotensin II, not ACTH (correct)

    Correct. The renin-angiotensin axis maintains aldosterone, so potassium stays normal.

  • B. Cortisol deficiency lowers urinary potassium loss

    Cortisol deficiency does not protect against hyperkalaemia; preserved aldosterone does.

  • C. The pituitary secretes a mineralocorticoid

    The pituitary secretes no mineralocorticoid; aldosterone comes from the adrenal cortex.

  • D. Low ACTH increases renin release

    ACTH has no major effect on renin release, so low ACTH does not raise it.

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.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Aldosterone is driven mainly by angiotensin II, not ACTH. In secondary adrenal failure ACTH is low, so cortisol falls, but the zona glomerulosa is controlled chiefly by angiotensin II and potassium, so aldosterone is preserved.

Why is "Cortisol deficiency lowers urinary potassium loss" not the answer?

Cortisol deficiency does not protect against hyperkalaemia; preserved aldosterone does.

Why is "The pituitary secretes a mineralocorticoid" not the answer?

The pituitary secretes no mineralocorticoid; aldosterone comes from the adrenal cortex.

Why is "Low ACTH increases renin release" not the answer?

ACTH has no major effect on renin release, so low ACTH does not raise it.

What concept does this question test?

It tests Endocrinology: secondary adrenal insufficiency in Physiology. Low ACTH also means no excess POMC-derived peptide, so there is no skin darkening.

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: secondary adrenal insufficiency?

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.