Effects of ovary suppression by a long-acting GnRH-agonist on circulating GH, insulin-like growth factor I and insulin levels in women with polycystic ovary syndrome

Our aim was to investigate the effect of GnRH-agonist (GnRH-a) induced suppression of plasma sex steroids on serum GH, insulin like growth factor-I (IGF-I) and insulin levels after an oral glucose load (OGTT) in women with polycystic ovary syndrome (PCOS). Serum insulin, GH and IGF-I levels during a 75-g 4-h OGTT were measured in 3 nonobese and 7 obese hyperandrogenic women with PCOS and normal glucose tolerance before and after 10 weeks of treatment with the GnRH-a triptorelin (3,75 mg im every 28 days). Basal estrogen and androgen levels were also measured at time 0 of the first and the second OGTT. After the therapy serum estrogens and androgens were significantly suppressed. Body weight remained unchanged. Basal GH significantly increased after the treatment while fasting IGF-I and insulin levels decreased from (mean +/- SE) 349.3 +/- 31.8 to 278.7 +/- 33.2 ng/mL and from 22.4 +/- 4.1 to 18.8 +/- 4.4 microU/mL, respectively. The insulin response to OGTT (area under curve) was also reduced (from 16,017 +/- 2598 to 11,736 +/- 2317 microU/mL/240 min). Our results suggest that the GnRH-a induced suppression of ovary secretion may modify the serum GH and IGF-I levels and the insulin response to an OGTT in women with PCOS.