Endocrinology: cortisol-binding globulin: 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: cortisol-binding globulin

Sample item

A woman taking oral oestrogen has a high total serum cortisol, but normal 24-hour urinary free cortisol, normal late-night salivary cortisol and no Cushingoid features. What explains the result?

AOestrogen raises ACTH through the pituitaryBHigher cortisol-binding globulin raises the bound fractionCOestrogen blocks hepatic metabolism of free cortisolDOestrogen stimulates the adrenal cortex to make more cortisol

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

The answer and the reasoning

B. Higher cortisol-binding globulin raises the bound fraction

Oestrogen increases hepatic synthesis of cortisol-binding globulin, which raises total cortisol while the free, biologically active fraction stays normal. Free cortisol measures, such as urinary or salivary cortisol, are therefore reliable.

Option by option

A. Oestrogen raises ACTH through the pituitary
Raised ACTH would raise free cortisol and urinary free cortisol as well.
B. Higher cortisol-binding globulin raises the bound fraction (correct)
Correct. More binding protein raises total cortisol without raising the free hormone.
C. Oestrogen blocks hepatic metabolism of free cortisol
Impaired clearance would raise free cortisol, and urinary free cortisol would not be normal.
D. Oestrogen stimulates the adrenal cortex to make more cortisol
Increased adrenal production would raise free cortisol and cause Cushingoid features.

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 B, Higher cortisol-binding globulin raises the bound fraction. Oestrogen increases hepatic synthesis of cortisol-binding globulin, which raises total cortisol while the free, biologically active fraction stays normal.

Why is "Oestrogen raises ACTH through the pituitary" not the answer?

Raised ACTH would raise free cortisol and urinary free cortisol as well.

Why is "Oestrogen blocks hepatic metabolism of free cortisol" not the answer?

Impaired clearance would raise free cortisol, and urinary free cortisol would not be normal.

Why is "Oestrogen stimulates the adrenal cortex to make more cortisol" not the answer?

Increased adrenal production would raise free cortisol and cause Cushingoid features.

What concept does this question test?

It tests Endocrinology: cortisol-binding globulin in Physiology. Free cortisol measures, such as urinary or salivary cortisol, are therefore reliable.

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: cortisol-binding globulin?

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.