Elevated bioactive luteinizing hormone in women with the polycystic ovary syndrome.

Serum measurements of bioactive (bio) luteinizing hormone (LH), immunoreactive (i) LH, iLH/follicle-stimulating hormone (FSH) ratios, serum androgens and estradiol (E2) were determined in 20 women with the clinical diagnosis of the polycystic ovary syndrome (PCO), and compared with the levels of 10 women with chronic anovulation (CA) and 10 control subjects in the early follicular phase. Women with CA and control subjects had similar levels of E2, androgens, bioLH, iLH, and iLH/FSH ratios. Fourteen of 20 women with PCO had levels of iLH exceeding 3 standard deviations (SD) of the levels of control women (21 mIU/ml), and 13 of 20 had iLH/FSH ratios above 3.2 (3 SD of control levels). Nineteen of 20 women, however, had bioLH levels above 70 mIU/ml (3 SD of control levels). Mean levels for bioLH were 131 +/- 18 in PCO, 39 +/- 3 in control subjects, and 40 +/- 3 in women with CA. The ratio of bioLH/iLH was 3.5 +/- 0.4 in control subjects and 3.2 +/- 0.3 in women with CA but significantly elevated in PCO (4.6 +/- 0.4, P less than 0.05). There was, however, a significant positive correlation between bioLH and iLH values in PCO (r = 0.64, P less than 0.01). A significant correlation was found between bioLH and serum testosterone as well as between bioLH and serum dehydroepiandrosterone sulfate (DHEA-S) (P less than 0.05), although no correlation was found between iLH and serum DHEA-S. Weight and obesity also did not correlate with either iLH or bioLH in women with PCO and CA. These data suggest that bioLH may be an important hormonal marker in the clinical diagnosis of PCO.