Effect of metformin on the growth hormone response to growth hormone-releasing hormone in obese women with polycystic ovary syndrome

Objective: Obese women with polycystic ovary syndrome (PCOS) show a marked growth hormone (GH) hyporesponsiveness to several stimuli. We aimed to evaluate the impact of insulin metabolism on the GH secretion impairment in these subjects in relation to food ingestion. Design: Prospective clinical study. Setting: Academic research center. Patient(s): Nine obese women with PCOS. Intervention(s): Metformin (1,500 mg/daily) was administered for three months. The study protocol, which was performed before and after therapy, included hormonal and lipid assays, oral glucose tolerance test (75 g), euglycemic hyperinsulinemic clamp, and growth hormone-releasing hormone (GHRH) test (50 μg/ev), both on fasting and after a standard meal. Main Outcome Measure(s): Growth hormone response to GHRH (expressed as the area under the curve) in different experimental conditions. Result(s): The preprandial GH response to GHRH was not modified by the therapy, whereas a significant increase (P<.05) occurred in the postprandial GH secretion, thus resembling the response of obese normal persons. This change was accompanied by a trend towards improvement, though not statistically significant, of all the evaluated glycoinsulinemic parameters. A significant reduction in cholesterol (P<.01) and androstenedione (P<.05) and an increase in sex hormone-binding globulin (P<.05) were also achieved. Conclusion(s): These data suggest that metformin is able to affect GH secretion in obese women with PCOS, even with minimal metabolic modifications. ©2005 by American Society for Reproductive Medicine.