Serum leptin concentrations in women during gonadotropin stimulation cycles

OBJECTIVE: To determine whether elevated follicular steroid levels during gonadotropin stimulation cycles are associated with altered circulating leptin concentrations. STUDY DESIGN: Sequential serum samples were collected from women (N = 37) undergoing luteal phase GnRH agonist + FSH treatment cycles prior to oocyte retrieval for in vitro fertilization. Leptin concentrations in serum were measured by radioimmunoassay and compared with serum estradiol, testosterone and dehydroepiandrosterone sulfate (DHEAS) levels. RESULTS: Serum leptin concentrations during stimulated cycles were variable between patients and correlated positively (r = .556, P < .01) with body mass index. Serum leptin levels correlated positively (r = .185, P < .05) with estradiol concentrations across all days. Mean serum leptin concentrations on the day gonadotropin treatment began (baseline, 12.9 +/- 2.0 ng/mL) were lower (P < .0001) than on the day peak estradiol levels were reached (18.4 +/- 2.3 ng/mL). Serum leptin concentrations also correlated with DHEAS levels (r = .214, P < .05) but did not correlate with testosterone or the estradiol:testosterone ratio. CONCLUSION Gonadotropin stimulation in women is associated with elevated leptin levels, consistent with an interaction between the reproductive axis and leptin secretion and/or clearance.