Lack of relationship between 17-hydroxyprogesterone response to buserelin testing and hyperinsulinemia in polycystic ovary syndrome

Objective: To determine whether hyperinsulinism affects cytochrome P450c 17α activity by investigating the correlation between 17–hydroxyprogesterone (17–OHP) hyper-responsiveness to the gonadotropin-releasing hormone (GnRH) agonist, buserelin, and the insulin response to oral glucose in polycystic ovary syndrome (PCOS). Design: Ultrasound, clinical and hormonal parameters were used to define PCOS in this prospective clinical study. We investigated the correlation between the 17–OHP response to buserelin testing and the insulin response to oral glucose in PCOS. Methods: Twenty-eight women with PCOS and eighteen normal women were included in the study. 17–OHP response to buserelin, and insulin and C–peptide responses to oral glucose were measured. Results: Twenty–live women with PCOS had an increased 17–OHP response. The PCOS patients showed significantly higher mean post–glucose load insulin and C–peptide levels than controls (P<0·05). No significant correlations were found between basal 17–OHP and fasting insulin or fasting C–peptide, between peak 17–OHP and fasting insulin, peak insulin or peak C–peptide, between 17–OHP area under the curve (AUC) and insulin AUC or C–peptide AUC, and between percent increment in 17–OHP and insulin AUC or C–peptide AUC (P >0·05). Conclusions: Lack of a relationship between the 17–OHP response to the GnRH agonist buserelin and hyperinsulinism suggests that hyperinsulinism may not play a role in the dysregulation of the cytochrome P450c17α enzyme seen in PCOS. European Journal of Endocrinology 136 410–415