Clinical biochemistry: adrenal enzyme defects: practice question

A Biochemistry 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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Biochemistry · Clinical biochemistry: adrenal enzyme defects

Sample item

A 3-year-old boy shows early pubic hair and a deepening voice, with blood pressure above the 99th centile and low serum potassium. Which pair of steroids accumulates?

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

The answer and the reasoning

A. 11-deoxycortisol and 11-deoxycorticosterone

11-Beta-hydroxylase deficiency blocks conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone to corticosterone. DOC has mineralocorticoid activity, so there is hypertension and hypokalaemia, and excess androgens cause virilisation. This separates it from 21-hydroxylase deficiency.

Option by option

  • A. 11-deoxycortisol and 11-deoxycorticosterone (correct)

    Correct. DOC excess causes hypertension and androgens virilise.

  • B. 17-hydroxyprogesterone and progesterone only

    Marked 17-hydroxyprogesterone rise typifies 21-hydroxylase deficiency, which causes salt wasting.

  • C. Pregnenolone and DHEA only

    Pregnenolone and DHEA excess without DOC would not cause hypertension.

  • D. Cortisol and aldosterone

    Cortisol and aldosterone would be low, not high.

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 Biochemistry question

What is the answer to this Biochemistry question?

The best answer is A, 11-deoxycortisol and 11-deoxycorticosterone. 11-Beta-hydroxylase deficiency blocks conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone to corticosterone.

Why is "17-hydroxyprogesterone and progesterone only" not the answer?

Marked 17-hydroxyprogesterone rise typifies 21-hydroxylase deficiency, which causes salt wasting.

Why is "Pregnenolone and DHEA only" not the answer?

Pregnenolone and DHEA excess without DOC would not cause hypertension.

Why is "Cortisol and aldosterone" not the answer?

Cortisol and aldosterone would be low, not high.

What concept does this question test?

It tests Clinical biochemistry: adrenal enzyme defects in Biochemistry. DOC has mineralocorticoid activity, so there is hypertension and hypokalaemia, and excess androgens cause virilisation. This separates it from 21-hydroxylase deficiency.

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 Clinical biochemistry: adrenal enzyme defects?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.