Effects of administration of 17β-oestradiol on serum leptin levels in healthy postmenopausal women

OBJECTIVE Women have higher leptin levels than men at a certain degree of adiposity, The role of oestrogens in the regulation of serum leptin levels remains inconclusive. The aim of the present study was to investigate the effect of unopposed oestrogen replacement therapy, during two months, on serum leptin levels in postmenopausal women. DESIGN A double-blind, placebo-controlled, randomized study. SUBJECTS Twenty-five healthy postmenopausal women were studied (mean (+/- SD) age: 52.9 +/- 2.7 years, range of age: 48.7-57.4years; mean body mass index (BMI): 26.4 +/- 4.2 kg/m(2), range of BMI: 21.0-39.0 kg/m(2)). Twelve of these women were treated with 2 mg 17 beta-oestradiol daily, and 13 postmenopausal women received placebo. MEASUREMENTS Before and at the end of a 2-month study period, anthropometric and bio-electrical impedance measurements were performed, and fasting blood samples were taken, to determine serum levels of sex hormones and leptin. RESULTS During the 2-month study period, body weight had increased significantly in the placebo group compared with the treatment group, but no significant changes were observed in percentage of body fat or the amount of body fat in kg between the groups. Following administration of 17 beta-estradiol, the median leptin level increased from 17.6 mu g/l to 24.1 mu g/l after 2 months (P = 0.008 compared with baseline). This increase was significantly different from the placebo group (P = 0.019), which showed no change in circulating leptin levels. CONCLUSION This study demonstrates that unopposed oestrogen replacement therapy during 2 months in postmenopausal women slightly, but significantly, increases total serum leptin levels. This observation suggests a role for oestrogens in the regulation of leptin.