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Non-classic congenital adrenal hyperplasia — SCE Endocrinology MCQ

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ModerateReproductive endocrinologyNon-classic congenital adrenal hyperplasiaSCE Endocrinology

A 27-year-old woman presents with hirsutism and irregular menses. Early-morning follicular 17-hydroxyprogesterone is borderline raised. After synacthen, 17-hydroxyprogesterone rises markedly. Cortisol response is adequate. What is the most likely diagnosis?

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Correct answer: A — Non-classic 21-hydroxylase deficiency

Non-classic 21-hydroxylase deficiency is best because marked ACTH-stimulated 17-hydroxyprogesterone elevation supports non-classic 21-hydroxylase deficiency. The alternatives are less appropriate because PCOS does not produce that steroid response; carcinoma causes rapid severe androgen excess; Cushing's has cortisol excess; aromatase deficiency is rare and presents differently. The SCE teaching point is to integrate the clinical pattern, biochemistry and context rather than treating an isolated result.

Reference: Endocrine Society congenital adrenal hyperplasia guideline