Endocrine: congenital adrenal hyperplasia: practice question

A Pathology 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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Pathology · Endocrine: congenital adrenal hyperplasia

Sample item

A 10-day-old genetically female infant has ambiguous genitalia, vomiting, hypotension, hyponatraemia and hyperkalaemia. Which enzyme is deficient and which precursor is raised?

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

The answer and the reasoning

C. 21-hydroxylase deficiency, with raised 17-hydroxyprogesterone

Classic 21-hydroxylase deficiency blocks cortisol and aldosterone synthesis. ACTH rises, causing adrenal hyperplasia, and precursors are diverted to androgens, which virilise a female fetus. Salt wasting, hyponatraemia, hyperkalaemia and hypotension appear in the first weeks, and 17-hydroxyprogesterone is the screening marker.

Option by option

  • A. 3-beta-hydroxysteroid dehydrogenase deficiency, with raised aldosterone

    3-beta-HSD deficiency blocks aldosterone production too, so aldosterone is low, not raised.

  • B. 11-beta-hydroxylase deficiency, with raised 11-deoxycorticosterone and hypertension

    11-beta-hydroxylase deficiency causes virilisation with hypertension from deoxycorticosterone excess.

  • C. 21-hydroxylase deficiency, with raised 17-hydroxyprogesterone (correct)

    Correct. Salt wasting with virilisation and raised 17-hydroxyprogesterone indicates 21-hydroxylase deficiency.

  • D. 17-alpha-hydroxylase deficiency, with hypertension and absent sex steroids

    17-alpha-hydroxylase deficiency causes hypertension with undervirilised genitalia in males and failure of puberty.

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 Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is C, 21-hydroxylase deficiency, with raised 17-hydroxyprogesterone. Classic 21-hydroxylase deficiency blocks cortisol and aldosterone synthesis.

Why is "3-beta-hydroxysteroid dehydrogenase deficiency, with raised aldostero…" not the answer?

3-beta-HSD deficiency blocks aldosterone production too, so aldosterone is low, not raised.

Why is "11-beta-hydroxylase deficiency, with raised 11-deoxycorticosterone an…" not the answer?

11-beta-hydroxylase deficiency causes virilisation with hypertension from deoxycorticosterone excess.

Why is "17-alpha-hydroxylase deficiency, with hypertension and absent sex ste…" not the answer?

17-alpha-hydroxylase deficiency causes hypertension with undervirilised genitalia in males and failure of puberty.

What concept does this question test?

It tests Endocrine: congenital adrenal hyperplasia in Pathology. ACTH rises, causing adrenal hyperplasia, and precursors are diverted to androgens, which virilise a female fetus. Salt wasting, hyponatraemia, hyperkalaemia and hypotension appear in the first weeks, and 17-hydroxyprogesterone is the screening marker.

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 Endocrine: congenital adrenal hyperplasia?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.