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Non-Classical Congenital Adrenal Hyperplasia — RACP Paediatrics MCQ

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HardEndocrinologyNon-Classical Congenital Adrenal HyperplasiaRACP Paediatrics

A 4-year-old boy presents with rapid growth, acne, pubic hair, and penile enlargement but prepubertal-sized testes. Serum testosterone is elevated, 17-hydroxyprogesterone is markedly elevated, and LH/FSH are suppressed. What is the most likely diagnosis?

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Correct answer: A — Non-classical congenital adrenal hyperplasia

Peripheral precocious puberty with elevated testosterone but suppressed gonadotrophins and prepubertal testes (indicating testicular origin is not the source) combined with markedly elevated 17-hydroxyprogesterone points to non-classical (late-onset) 21-hydroxylase deficiency CAH. The excess adrenal androgens cause virilisation without testicular enlargement. ACTH stimulation testing and CYP21A2 genotyping confirm the diagnosis.

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Congenital Adrenal Hyperplasia