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Congenital adrenal hyperplasia — RACP Paediatrics MCQ

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ModerateEndocrineCongenital adrenal hyperplasiaRACP Paediatrics

A female neonate presents at day 5 with ambiguous genitalia, poor feeding, vomiting, and progressive weight loss. Blood tests show hyponatraemia (Na 125), hyperkalaemia (K 7.2), and hypoglycaemia. 17-hydroxyprogesterone is markedly elevated. What is the most likely diagnosis?

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Correct answer: C — Congenital adrenal hyperplasia (21-OH deficiency)

A salt-wasting crisis in a neonate with ambiguous genitalia (46,XX virilisation), hyponatraemia, hyperkalaemia, hypoglycaemia, and elevated 17-OHP is classic for congenital adrenal hyperplasia (21-hydroxylase deficiency). This is a life-threatening emergency requiring immediate IV hydrocortisone, fluid resuscitation, and dextrose.

Reference: RCH Melbourne – 2023 – Congenital Adrenal Hyperplasia CPG; RACP Paediatric Curriculum – Endocrine