ANDROGEN PRODUCTION AND SKIN METABOLISM IN HIRSUTISM

The concentrations of testosterone, androstenedione and dihydrotestosterone (DHT) in the plasma and 5α-androstane-3α,17β-diol (androstanediol) in the urine were measured in 40 women with hirsutism of ovarian, adrenal and idiopathic origin. Conversion of [3H]testosterone to DHT, 3α- and 3β-androstanediols was also studied in homogenates of pubic skin obtained from 15 of the patients. Results were compared with values obtained from normal men and women. Values for the levels of testosterone, DHT and androstenedione in the plasma and androstanediol in the urine of hirsute women were all above control levels, especially for plasma androstenedione and urinary androstanediol (P < 0·001). This finding was particularly marked in patients with hirsutism of ovarian origin. Conversion of [3H]testosterone to 5α-reduced metabolites by homogenates of skin obtained from hirsute women was significantly greater than by homogenates of skin from normal women (P < 0·001) but was the same as the value for normal men. The highest values for conversion were obtained from the patients with idiopathic hirsutism. These results indicate that androstenedione is the principal androgen secreted in hirsutism. In sexual skin this steroid may be converted to DHT and 3α-, and 3β-androstanediols and the increased activity of testosterone 5α-reductase may result in an exaggerated 'utilization' of androstenedione in this tissue. The high rate of excretion of androstanediol in the urine of patients with idiopathic hirsutism may be explained by the fact that this steroid is an end-product of testosterone metabolism.