Role of sex-hormone-binding globulin and free sex steroid hormones in hyperandrogenic anovulation.

To clarify the mechanism of hyperandrogenic anovulation, the binding capacity of sex-hormone-binding globulin (SHBG-BC), the levels of free steroid hormones, and the levels of basal serum testosterone (T), estradiol (E2), estrone (E1) and gonadotropins were determined in 42 hyperandrogenic anovulatory women. The mean levels of basal T (0.74 +/- 0.04 ng/ml, p less than 0.001), free T (3.07 +/- 0.51 ng/dl, p less than 0.01) and free E2 (2.26 +/- 0.27 pg/ml, p less than 0.05), basal luteinizing hormone (LH) (33.4 +/- 2.7 mIU/ml, p less than 0.001), responsiveness of LH (180.7 +/- 21.5 mIU/ml, p less than 0.001) after luteinizing hormone releasing hormone (LHRH) administration, and the basal LH/basal follicle stimulating hormone (FSH) ratio (3.42 +/- 0.25, p less than 0.001) in the patients were significantly higher, the SHBG-BC level (1.76 +/- 0.33 micrograms DHT bound/dl, p less than 0.05) significantly reduced, and basal levels of E2 (38.0 +/- 3.2 pg/ml) and E1 (110 +/- 13 pg/ml) unchanged compared to the controls. These findings suggest that increased T in hyperandrogenic anovulatory women results in decreased SHBG-BC and increased free T and E2 which might be the cause of inappropriate gonadotropin secretion followed by chronic anovulation.