Comparison between 1 year oral and transdermal oestradiol and sequential norethisterone acetate on circulating concentrations of leptin in postmenopausal women

BACKGROUND: Oral and transdermal postmenopausal hormone replacement therapy (HRT) affects lipid and glucose metabolism differently, which is of signif icance in the release of leptin by adipocytes. Moreover, oestrogen and prog esterone can stimulate leptin secretion in women of reproductive age. There fore, we compared the effects of oral and transdermal oestrogen plus proges tin regimen on plasma leptin in 38 healthy postmenopausal women with normal body mass index (BMI), who wished to use HRT to control incapacitating cli macteric symptoms. METHODS: The women were randomized to treatment with ora l HRT (2 mg oestradiol on days 1-12, 2 mg oestradiol plus I mg norethistero ne acetate (NETA) on days 13-22, and 1 mg oestradiol on days 23-28, n = 19) , or with transdermal HRT (50 mug/day of oestradiol on days 1-13, and 50 mu g oestradiol plus 250 mug/day NETA on days 14-28, n = 19) for 1 year. Plasm a samples were collected before and at oestradiol + NETA phase after 2, 6 a nd 12 months treatment and were assayed for leptin. RESULTS: The baseline l eptin, ranging from 3.3 to 34.9 mug/l, was significantly associated with BM I (r = 0.78, P < 0.0001), but showed no difference between women in oral HR T (geometric mean 13.9 mug/l, 95% confidence interval (CI) 10.1-17.6 mug/l) or transdermal HRT group (geometric mean 12.0 mug/l, 95% CI 9.7-14.3 mug/l ). Neither oral nor transdermal oestradiol + NETA caused any significant ch anges in plasma leptin (or BMI) after 2, 6, or 12 months of treatment. CONC LUSION: Leptin is an unsuitable factor to detect oestradiol + NETA-induced metabolic changes in postmenopausal women.