Endocrinology: loss of cortisol feedback after adrenalectomy: 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: loss of cortisol feedback after adrenalectomy

Sample item

A woman who underwent bilateral adrenalectomy for pituitary-dependent Cushing disease later develops darkening of the skin and an enlarging sellar mass with a very high plasma ACTH. What best explains the new mass?

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

The answer and the reasoning

A. Loss of cortisol feedback allowing adenoma growth

After adrenalectomy there is no cortisol to restrain corticotrophs, so a pre-existing pituitary adenoma can enlarge and secrete large amounts of ACTH and related peptides, causing pigmentation (Nelson syndrome). The sellar mass points to the pituitary as the source.

Option by option

  • A. Loss of cortisol feedback allowing adenoma growth (correct)

    Correct. Loss of negative feedback by cortisol allows the corticotroph tumour to enlarge and oversecrete ACTH.

  • B. Compensatory hyperplasia of a retained accessory adrenal gland

    An accessory adrenal remnant would make cortisol, which would suppress ACTH rather than raise it.

  • C. Ectopic ACTH secretion from a bronchial tumour

    Ectopic ACTH would not explain an enlarging sellar mass.

  • D. Release of the pituitary from dopaminergic inhibition

    Dopamine restrains lactotrophs, not corticotrophs, so this does not explain a corticotroph mass.

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, Loss of cortisol feedback allowing adenoma growth. After adrenalectomy there is no cortisol to restrain corticotrophs, so a pre-existing pituitary adenoma can enlarge and secrete large amounts of ACTH and related peptides, causing pigmentation (Nelson syndrome).

Why is "Compensatory hyperplasia of a retained accessory adrenal gland" not the answer?

An accessory adrenal remnant would make cortisol, which would suppress ACTH rather than raise it.

Why is "Ectopic ACTH secretion from a bronchial tumour" not the answer?

Ectopic ACTH would not explain an enlarging sellar mass.

Why is "Release of the pituitary from dopaminergic inhibition" not the answer?

Dopamine restrains lactotrophs, not corticotrophs, so this does not explain a corticotroph mass.

What concept does this question test?

It tests Endocrinology: loss of cortisol feedback after adrenalectomy in Physiology. The sellar mass points to the pituitary as the source.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: loss of cortisol feedback after adrenalectomy?

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.