Quantitation of 5α-androstanedione in normal women and women with PCOS.

In vitro studies show that 5α-androstane-3,17-dione (5α-A) is an important intermediate in the formation of dihydrotestosterone (DHT) from androstenedione (A) in women and men. Many studies involving hyperandrogenism, hirsutism, and polycystic ovary syndrome (PCOS) have measured A, testosterone (T), and DHT, but not 5α-A due to lack of a readily available assay to quantify this androgen. We have developed a specific and sensitive radioimmunoassay to measure 5α-A levels, together with A, T, and DHT, in both serum and genital skin. The present study involves 2 cohorts. Cohort 1 included 23 mostly postmenopausal women who provided both serum and genital skin to measure those androgens. In cohort 2, serum androgen levels were compared between women with PCOS and non-PCOS controls. Tissue-to-serum ratios were significantly higher for 5α-A and DHT as compared to A and T. None of the androgens showed a significant correlation between serum and genital tissue. In serum, 5α-A was significantly correlated with A, T, and DHT. In cohort 2, A, T, and DHT were significantly higher in the PCOS group compared to the control group. In contrast, 5α-A levels were similar between the 2 groups. Our findings support the view that 5α-A is an important intermediate in DHT formation in genital skin. Also, the relatively low levels of 5α-A in PCOS women suggest that it may play a more important intermediate role in the conversion of A to androsterone glucuronide.