Effect of hormone replacement therapy and tibolone on serum leptin levels in postmenopausal women

Abstract

Objective: To evaluate the effect of estrogen replacement therapy (ERT), continuous combined hormone replacement therapy (HRT) and tibolone on serum leptin levels in healthy postmenopausal women. Methods: Eighty-four healthy postmenopausal women aged 43–63 years were studied prospectively. Hysterectomized women ( n=16) received conjugated equine estrogens (CEE) 0.625 mg. Women with an intact uterus were randomly allocated either to CEE+medroxyprogesterone acetate (CEE/MPA) 5 mg or tibolone 2.5 mg. Serum leptin levels were assessed at baseline and after 6 months of treatment. Results: The three groups did not differ with respect to age, body mass index (BMI) or baseline serum leptin levels. Overweight women (BMI>25 kg/m 2) had higher baseline leptin levels (27.0±11.4 ng/ml) compared to their lean counterparts (BMI≤25 kg/m 2; leptin: 16.5±8.1 ng/ml, P=0.0001). Neither CEE nor CEE/MPA had any effect on serum leptin levels at the end of 6 months either in overweight or in lean women (overweight: CEE baseline 34.4±13.3 ng/ml, 6 months 36.9±15.8, P=0.89, CEE/MPA baseline 22.4±9.8 ng/ml, 6 months 26.8±8.7 ng/ml, P=0.1; lean: CEE baseline 12.6±4.4 ng/ml, 6 months 13.2±5.8 ng/ml, P=0.36, CEE/MPA baseline 17.2±10.6 ng/ml, 6 months 18.8±8.8 ng/ml, P=0.31). Similarly serum leptin remained unchanged at the end of the study in both lean and overweight women on tibolone (overweight: baseline 22.9±8.1 ng/ml, 6 months 18.5±12 ng/ml, P=0.37; lean: baseline 13.2±5.6 ng/ml, 6 months 17.3±8.4 ng/ml). Conclusion: BMI is a strong determinant of serum leptin levels in healthy postmenopausal women. Neither ERT/HRT nor tibolone exert any effect on serum leptin after 6 months in lean or overweight postmenopausal women. Further studies are required to verify the exact role of estrogen and tibolone on leptin production and function in postmenopausal women.