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Congenital Adrenal Hyperplasia — RACP Paediatrics MCQ

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ModerateEndocrinologyCongenital Adrenal HyperplasiaRACP Paediatrics

A newborn female presents on day 5 of life with vomiting, dehydration, and shock. Serum sodium is 118 mmol/L and potassium is 8.2 mmol/L. The external genitalia show clitoromegaly and labial fusion. 17-hydroxyprogesterone is markedly elevated. What is the diagnosis?

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Correct answer: A — Congenital adrenal hyperplasia (21-hydroxylase deficiency) – salt-wasting form

Salt-wasting 21-hydroxylase deficiency (the most common form of CAH) presents in females with virilised genitalia (due to excess androgens) and in both sexes with adrenal crisis (hyponatraemia, hyperkalaemia, dehydration, shock) in the first 1–3 weeks of life. Markedly elevated 17-hydroxyprogesterone confirms the diagnosis. Emergency treatment includes IV hydrocortisone, fluid resuscitation, and fludrocortisone.

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