Changes in forearm bone mass and bone size after menopause - A mean 24-year prospective study.

Objective: Bone loss and periosteal expansion is found after menopause. The accelerated early postmenopausal bone loss is not permanent but if the same accounts for the periosteal expansion is unknown. Methods: Bone mineral density (BMD) and skeletal structure of the distal forearm were followed from menopause and on average 24 years (range 18-28) by single-photon absorptiometry at 12 occasions in a population-based sample of 81 Caucasian women with no medication or disease affecting bone metabolism. A Strength Index based on areal BMD and bone structure was calculated. Postmenopausal serum-estradiol levels and incident distal radius fractures were registered. Data are presented as means with 95% confidence interval (95% CI). Results: The annual BMD loss in three periods, 0-8, 8-16 and 16-28 years after menopause, was 2.0% (1.6, 2.4), 1.0% (0.6, 1.4) and 1.0% (0.7, 1.3), respectively. The annual periosteal expansion was 1.0% (0.8, 1.3), 0.0% (-0.3, 0.3) and 0.0% (-0.2, 0.2), respectively. Mean post-menopausal oestrogen levels correlated moderately with annual loss in aBMD (r=0.51, p<0.001) but less with the annual changes in bone width (r= -0.22, p=0.06). Conclusion: Postmenopausal periosteal expansion in the distal forearm seems to occur only in the first postmenopausal decade.