Differential Diagnosis of Nonclassic CAH and PCOS Based on Urinary Steroid Profiling by Gas Chromatography–Mass Spectrometry

This article presents a clinical case of hyperandrogenism in a 19-year-old female patient. She presented with pronounced symptoms and was found to be a heterozygous carrier of three pathogenic variants in the CYP21A2 gene. Hyperandrogenism was confirmed by laboratory tests, and imaging studies of the adrenal glands and ovaries were performed. Steroid profiling of 24-hour urine gas chromatography-mass spectrometry indicated an ovarian source of hyperandrogenism. Additional genetic testing revealed that the patient’s mother is a compound heterozygote for four pathogenic variants. A gene conversion event resulted in the patient carrying three heterozygous pathogenic variants on a single chromosome. The final diagnosis was polycystic ovary syndrome. Given her status as a heterozygous carriage in the 21-hydroxylase gene, she was prescribed a combined oral contraceptive, which proved effective. This case underscores the diagnostic challenge in differentiating between polycystic ovary syndrome and nonclassic congenital adrenal hyperplasia in patients with hyperandrogenism.