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 mu g/day plus oral sequential dydrogesterone 10 mg/day for 14 of 28 days per cycle (n = 20). Body composition was measured at the baseline 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.