The effect of hormone replacement therapy on appendicular lean tissue mass in early postmenopausal women

The impact of hormone replacement therapy (HRT) on skeletal muscle mass is still a controversial issue in women's health. Some authors hypothesize anabolic effects, others catabolic. These hypotheses, however, await confirmation by longitudinal observations based on more direct measurements of muscle mass. The aim of the present preliminary study was to evaluate the effect of a 3-year HRT program on appendicular lean tissue mass (LTM(A)) in early postmenopausal women aged 45-54 years.

This was a randomized, double-blind and placebo-controlled trial. Women received HRT with 2 mg estradiol valerate combined either continuously with 1 mg cyproterone acetate (days 1-28; n = 15) or sequentially with 75 mug levonorgestrel (days 17-28; n = 15), or placebo (n = 18). Serum estradiol was measured by radioimmunoassay. LTM(A) was measured by dual photon absorptiometry (baseline) and dual energy X-ray absorptiometry (years 2 and 3).

Baseline serum estradiol did not show significant correlation with the respective LTM(A) (r = 0.018, p = 0.88, n = 75). Cross-sectional analysis found no significant differences between the intervention groups at any time points. The longitudinal changes between years 2 and 3 showed a trend toward decreasing LTM(A) in those receiving HRT (-0.08 +/- 0.12 kg, n = 30) compared to those receiving placebo (0.12 +/- 0.25 kg, n = 18, p = 0.44).

The present preliminary study did not find significant effects on LTM(A) caused by HRT. The trends toward decreasing LTM(A) in the HRT groups might suggest catabolic rather than anabolic effects. These trends, however, await confirmation by larger clinical trials.