Gynaecological endocrinology: non-classic 21-hydroxylase deficiency: practice question

A OBG 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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OBG · Gynaecological endocrinology: non-classic 21-hydroxylase deficiency

Sample item

A 22-year-old has hirsutism, acne and irregular cycles. Non-classic 21-hydroxylase deficiency is suspected because an early-morning follicular-phase steroid precursor is borderline raised. Which test confirms the diagnosis?

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

The answer and the reasoning

B. Cosyntropin (ACTH) stimulation test

In late-onset CAH, a borderline basal 17-hydroxyprogesterone is confirmed by an exaggerated rise after cosyntropin. The test separates it from PCOS, which looks similar clinically.

Option by option

  • A. Oral glucose tolerance test

    Glucose tolerance testing assesses insulin resistance and not adrenal enzyme defects.

  • B. Cosyntropin (ACTH) stimulation test (correct)

    Correct. An exaggerated 17-hydroxyprogesterone response after ACTH confirms the enzyme block.

  • C. GnRH stimulation test

    GnRH stimulation tests gonadotropin reserve, for example in delayed puberty.

  • D. Overnight dexamethasone suppression test

    Dexamethasone suppression is a screening test for Cushing syndrome.

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 OBG questions

Questions about this OBG question

What is the answer to this OBG question?

The best answer is B, Cosyntropin (ACTH) stimulation test. In late-onset CAH, a borderline basal 17-hydroxyprogesterone is confirmed by an exaggerated rise after cosyntropin.

Why is "Oral glucose tolerance test" not the answer?

Glucose tolerance testing assesses insulin resistance and not adrenal enzyme defects.

Why is "GnRH stimulation test" not the answer?

GnRH stimulation tests gonadotropin reserve, for example in delayed puberty.

Why is "Overnight dexamethasone suppression test" not the answer?

Dexamethasone suppression is a screening test for Cushing syndrome.

What concept does this question test?

It tests Gynaecological endocrinology: non-classic 21-hydroxylase deficiency in OBG. The test separates it from PCOS, which looks similar clinically.

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 Gynaecological endocrinology: non-classic 21-hydroxylase deficiency?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG 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.