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DSD Initial Investigation — RACP Paediatrics MCQ

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ModerateGenetics & MetabolicDSD Initial InvestigationRACP Paediatrics

A newborn is found to have bilateral undescended testes and hypospadias. The infant has ambiguous genitalia. What is the most important initial investigation?

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Correct answer: D — Karyotype and urgent endocrine evaluation (17-OHP, electrolytes)

Ambiguous genitalia with bilateral undescended testes requires urgent evaluation for disorders of sex development (DSD). 17-OHP is critical to exclude salt-wasting CAH (which can cause life-threatening adrenal crisis in the first 1-2 weeks). Karyotype and electrolytes should be checked urgently. Sex assignment should be deferred until evaluation is complete.

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: DSD