Differential impact of conventional oral or transdermal hormone replacement therapy or tibolone on body composition in postmenopausal women

OBJECTIVE: To compare the effects on body composition and body weight of tibolone vs two different sequential oral or transdermal oestrogen-progestogen hormone replacement therapies versus no therapy. PATIENTS AND METHODS: One hundred postmenopausal women were assigned to a control group (n = 26), or randomized to 1) tibolone (TIB) 2.5 mg/day (n = 28), 2) oral oestradiol 2 mg/day (PO) plus sequential dydrogesterone 10 mg/day for 14 of 28 days per cycle (n = 26), or 3) transdermal oestradiol patch (TTS) releasing 50 micrograms/day plus oral sequential dydrogesterone 10 mg/day for 14 of 28 days per cycle (n = 20). Body composition was measured at the base-line and every 6 months for 2 years by DXA (Hologic QDR 1000 W). RESULTS: Total body fat mass increased (P < 0.05) in controls (+3.6 +/- 1.5%) and in TTS treated (+4.7 +/- 2.2%), but not in PO (-1.2 +/- 2.4%) and TIB (-1.6 +/- 2.2%) treated subjects. This increase in total fat mass in controls and TTS treated women was mostly due to an increase in fat mass of the trunk (P < 0.05), but not legs. As a result, a redistribution of body fat to the trunk occurred in controls, TTS and TIB, but not in PO treated women (P < 0.05). Total lean body mass decreased (P < 0.02) in controls (-1.7 +/- 0.7%) and PO (-1.4 +/- 0.6%) but not in TTS (+0.3 +/- 0.8%) and TIB (+0.4 +/- 0.5%) treated subjects. CONCLUSIONS: The menopause is associated with an increase in total body fat and a decline in lean body mass. Oral oestradiol/dydrogesterone and tibolone prevent total body fat changes, whereas transdermal oestradiol/oral dydrogesterone and tibolone prevent the lean mass changes. Furthermore, oral oestradiol/dydrogesterone prevents the shift to a central, android fat distribution.