Simple virilizing form of 21-hydroxylase deficiency presenting with renal Insufficiency and polycythemia: a case report.

The simple virilizing (SV) form of 21-hydroxylase deficiency (21-OHD) is primarily characterized by androgen excess. Gonadal dysfunction is widely acknowledged; however, systemic complications, including renal injury, are often overlooked. This report presents a rare case involving a 25-year-old female diagnosed with SV 21-OHD, who subsequently experienced unanticipated renal insufficiency and secondary polycythemia. Genetic analysis confirmed compound heterozygous mutations in the CYP21A2 gene. The patient demonstrated significant hyperandrogenemia and polycythemia driven by erythropoietin. Following erythrocytapheresis and glucocorticoid replacement therapy, androgen levels normalized, resulting in marked renal function recovery and resolution of polycythemia. This case and a mechanistic review illustrate the potential interplay between chronic hyperandrogenism, erythropoiesis dysregulation, and kidney injury, underscoring the importance of timely hormonal management for the preservation of long-term renal function in CAH (Congenital adrenal hyperplasia).