Non-classic congenital adrenal hyperplasia — SCE Endocrinology MCQ

Correct answer: D — Non-classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency

The best answer is “Non-classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency”. Inadequate 21-hydroxylation causes accumulation of 17-hydroxyprogesterone, especially after ACTH stimulation; non-classic disease commonly presents later with hyperandrogenism and menstrual dysfunction. “Polycystic ovary syndrome causing basal androgen excess” is less appropriate because PCOS can overlap clinically but does not produce the diagnostic stimulated steroid pattern “Complete androgen insensitivity with absent Müllerian structures” is less appropriate because complete androgen insensitivity presents with a female phenotype, absent uterus and scant body hair rather than hirsutism “An androgen-secreting ovarian tumour as the expected Synacthen response” is less appropriate because an ovarian tumour does not cause ACTH-dependent 17-hydroxyprogesterone accumulation “Cushing disease caused by autonomous pituitary ACTH” is less appropriate because Cushing disease has a different steroid phenotype and would not specifically establish this enzymatic block

Reference: Society for Endocrinology clinical guidance: Management of adults with congenital adrenal hyperplasia. https://www.endocrinology.org/clinical-practice/clinical-guidance/society-for-endocrinology-guidance/