Endocrinology and diabetes: work-up after Cushing screen: practice question

A General Medicine 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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General Medicine · Endocrinology and diabetes: work-up after Cushing screen

Sample item

A 35-year-old woman has weight gain, purple striae, proximal weakness and hypertension. Her morning cortisol after 1 mg of dexamethasone at night is 9 micrograms/dL (not suppressed), and 24-hour urinary free cortisol is raised. Which investigation should be done next to find the cause?

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

The answer and the reasoning

A. Plasma ACTH measurement

After biochemical confirmation of Cushing syndrome, the plasma ACTH level separates ACTH-dependent from ACTH-independent causes. A suppressed ACTH points to an adrenal source and leads to adrenal CT, while a normal or raised value leads to pituitary MRI and, if needed, inferior petrosal sinus sampling.

Option by option

  • A. Plasma ACTH measurement (correct)

    Correct. ACTH level decides the direction of further imaging.

  • B. Inferior petrosal sinus sampling

    Petrosal sinus sampling is reserved for equivocal ACTH-dependent cases after imaging.

  • C. CT of the adrenal glands

    Adrenal CT is appropriate once ACTH is found to be suppressed.

  • D. MRI of the pituitary gland

    Pituitary MRI is chosen only after ACTH is found to be non-suppressed, and may miss microadenomas.

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.

More General Medicine questions

Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is A, Plasma ACTH measurement. After biochemical confirmation of Cushing syndrome, the plasma ACTH level separates ACTH-dependent from ACTH-independent causes.

Why is "Inferior petrosal sinus sampling" not the answer?

Petrosal sinus sampling is reserved for equivocal ACTH-dependent cases after imaging.

Why is "CT of the adrenal glands" not the answer?

Adrenal CT is appropriate once ACTH is found to be suppressed.

Why is "MRI of the pituitary gland" not the answer?

Pituitary MRI is chosen only after ACTH is found to be non-suppressed, and may miss microadenomas.

What concept does this question test?

It tests Endocrinology and diabetes: work-up after Cushing screen in General Medicine. A suppressed ACTH points to an adrenal source and leads to adrenal CT, while a normal or raised value leads to pituitary MRI and, if needed, inferior petrosal sinus sampling.

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 and diabetes: work-up after Cushing screen?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.