Endocrinology: CAH in a girl: practice question

A Pediatrics 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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Pediatrics · Endocrinology: CAH in a girl

Sample item

A newborn with 46,XX karyotype has clitoral enlargement and fused labioscrotal folds. Which is the likely cause?

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

The answer and the reasoning

B. Excess androgens from 21-hydroxylase deficiency

In CAH, blocked cortisol synthesis shunts precursors into androgen pathways, virilising a female fetus with normal ovaries and uterus. Androgen insensitivity occurs in 46,XY with female phenotype. Salt-wasting must be anticipated and treated.

Option by option

  • A. Androgen insensitivity syndrome

    AIS occurs in 46,XY individuals.

  • B. Excess androgens from 21-hydroxylase deficiency (correct)

    Correct. Prenatal androgen excess virilises the 46,XX fetus.

  • C. Klinefelter syndrome

    Klinefelter syndrome is 47,XXY.

  • D. 5-alpha-reductase deficiency

    5-alpha-reductase deficiency occurs in 46,XY.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is B, Excess androgens from 21-hydroxylase deficiency. In CAH, blocked cortisol synthesis shunts precursors into androgen pathways, virilising a female fetus with normal ovaries and uterus.

Why is "Androgen insensitivity syndrome" not the answer?

AIS occurs in 46,XY individuals.

Why is "Klinefelter syndrome" not the answer?

Klinefelter syndrome is 47,XXY.

Why is "5-alpha-reductase deficiency" not the answer?

5-alpha-reductase deficiency occurs in 46,XY.

What concept does this question test?

It tests Endocrinology: CAH in a girl in Pediatrics. Androgen insensitivity occurs in 46,XY with female phenotype. Salt-wasting must be anticipated and treated.

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 Endocrinology: CAH in a girl?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.