Difference in the effects of body composition on bone mineral density between pre- and postmenopausal women.

OBJECTIVE

This study was to investigate whether the effect of lean and fat mass component on bone mineral density (BMD) differs between pre- and postmenopausal women.

MATERIALS AND METHODS

Subjects were 360 pre- and 193 postmenopausal Japanese women with right side dominance. Age, height, and years since menopause (YSM, in postmenopausal women) were recorded. Body fat and lean body mass were measured by whole body scanning with dual-energy X-ray absorptiometry (DEXA). BMD of the vertical axis (L2-4 of the lumbar spine, pelvis, bilateral legs, and total body) and horizontal axis (arms) were also measured by DEXA.

RESULTS

In premenopausal women, lean body mass was independently correlated with BMD of the left arm (partial correlation coefficient = 0.417), right arm (0.430), L2-4 (0.285), pelvis (0.276), left leg (0.403), right leg (0.412), and total body (0.377) (P < 0.001). However, body fat mass was not correlated with several BMD sites except for pelvis BMD (0.187, P < 0.01). In postmenopausal women, body fat mass was independently correlated with BMD of the left arm (0.248, P < 0.01), L2-4 (0.188, P < 0.05), pelvis (0.263, P < 0.01), left leg (0.228, P < 0.01), right leg (0.319, P < 0.001), and total body (0.188, P < 0.01)). However, lean body mass was correlated with BMD in only three segmental regions including left arm (0.175), right arm (0.217), and left leg (0.210; P < 0.05).

CONCLUSION

Lean body mass is a significant determinant of BMD in premenopausal women, while body fat mass is a significant determinant in postmenopausal women.