Increased Bioactive Luteinizing Hormone Levels and Bio/Immuno Ratio in Women with Hyperthecosis of the Ovaries: Possible Role of Hyperinsulinemia1

Abstract

Unlike women with polycystic ovarian disease, women with hyperthecosis have normal or low immunoactive LH levels. They have severe insulin resistance with marked hyperinsulinemia. Bioactive LH levels have not been studied in these women. The purpose of this study was to investigate 1) whether there is an increase in bioactive LH levels in women with hyperthecosis of the ovaries and 2) whether hyperinsulinemia has an effect on LH secretion. Six women with hyperthecosis of the ovaries confirmed by histological examination were included in the study. Six normal women in the midproliferative phase of the cycle served as controls. All women were admitted to the Clinical Research Center at 0800 h, and blood samples were obtained every 15 min for 6 h. All samples were assayed for LH by RIA and bioassay. The PC Pulsar Program was used for pulse analysis of LH secretion. Patients with hyperthecosis had significantly higher (P < 0.002) bioactive LH levels (66.9 ± 13 mIU/mL) than controls (29.3 ± 6 mIU/mL). Immunoactive LH levels in hyperthecosis were not significantly different from those in control women. Significantly higher bio/immuno LH ratios (P < 0.001) were observed in women with hyperthecosis (6.2 ± 0.9) than in normal control women (2.4 ± 0.5). There was a significant positive correlation between insulin levels and the bio/immuno ratio of LH. Pulse amplitude and interpulse intervals for immunoactive LH in hyperthecosis patients were similar to those in control women. The pulse amplitude of bioactive LH was significantly higher (P < 0.01) in women with hyperthecosis compared to that in normal controls. Hyperinsulinemia induced during LH sampling resulted in increased bioactive LH levels with no change in immunoactive LH. These results indicate that 1) women with hyperthecosis of the ovaries have increased secretion of biologically active LH, and 2) hyperinsulinemia may enhance the secretion of the biologically active form of LH.