Gynaecological endocrinology: congenital adrenal hyperplasia: 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: congenital adrenal hyperplasia

Sample item

A newborn with 46,XX karyotype has an enlarged clitoris and fused labioscrotal folds. On day 8 she is vomiting and dehydrated with sodium 123 mmol/L and potassium 7.1 mmol/L. Which investigation confirms the diagnosis?

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

The answer and the reasoning

D. Serum 17-hydroxyprogesterone

Salt-wasting 21-hydroxylase deficiency causes cortisol and aldosterone deficiency with androgen excess, producing virilisation of a female fetus and an adrenal crisis in the first weeks. Markedly raised 17-hydroxyprogesterone confirms the diagnosis, and treatment is hydrocortisone with fludrocortisone and saline. The internal genitalia are normal female structures.

Option by option

  • A. Serum oestradiol

    Oestradiol is not the marker of this condition.

  • B. Serum cortisol only at 8 am

    A single cortisol level is not diagnostic as the precursor level is the key.

  • C. Serum prolactin

    Prolactin does not help in diagnosing adrenal enzyme defects.

  • D. Serum 17-hydroxyprogesterone (correct)

    Correct. 17-hydroxyprogesterone is the diagnostic marker of 21-hydroxylase deficiency.

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 OBG question

What is the answer to this OBG question?

The best answer is D, Serum 17-hydroxyprogesterone. Salt-wasting 21-hydroxylase deficiency causes cortisol and aldosterone deficiency with androgen excess, producing virilisation of a female fetus and an adrenal crisis in the first weeks.

Why is "Serum oestradiol" not the answer?

Oestradiol is not the marker of this condition.

Why is "Serum cortisol only at 8 am" not the answer?

A single cortisol level is not diagnostic as the precursor level is the key.

Why is "Serum prolactin" not the answer?

Prolactin does not help in diagnosing adrenal enzyme defects.

What concept does this question test?

It tests Gynaecological endocrinology: congenital adrenal hyperplasia in OBG. Markedly raised 17-hydroxyprogesterone confirms the diagnosis, and treatment is hydrocortisone with fludrocortisone and saline. The internal genitalia are normal female structures.

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 Gynaecological endocrinology: congenital adrenal hyperplasia?

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.