Serum leptin concentrations in women during gonadotropin stimulation cycles

OBJECTIVE: To determine whether elevated follicular steroid levels during g onadotropin stimulation cycles are associated with altered circulating lept in concentrations. STUDY DESIGN: Sequential serum samples were collected from women (N = 37) u ndergoing luteal phase GnRH agonist + FSH treatment cycles prior to oocyte retrieval for in vitro fertilization. Leptin concentrations in serum were m easured 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 m ass index. Serum leptin levels correlated positively (r = .185, P < .05) wi th estradiol concentrations across all days. Mean serum leptin concentratio ns on the day gonadotropin treatment began (baseline, 12.9 +/- 2.0 ng/mL) w ere lower (P < .0001) than on the day peak estradiol levels were reached (1 8.4 +/- 2.3 ng/mL). Serum leptin concentrations also correlated with DHEAS levels (r = .214, P < .05) but did not correlate with testosterone or the e stradiol:testosterone ratio. CONCLUSION Gonadotropin stimulation in women is associated with elevated le ptin levels, consistent with an interaction between the reproductive axis a nd leptin secretion and/or clearance.