To What Extent Is Bone Mineral Density Determined By Body Composition In Brazilian Postmenopausal Women?

Abstract

2051 Previous study of the relative importance of fat mass (FM) and Fat Free Mass (FFM) as a determinant of bone mineral density (BMD) have yielded discordant results. Additionally, Aloia et al. (1995) reported that bone mass may be partially influenced by race. PURPOSE: The aim of this study was to determine to what extent bone mineral density (BMD) is determined by body mass (BM), FM, and FFM in healthy Brazilian postmenopausal women. METHODS: Total body composition and regional bone mass were measured in 97 sedentary, healthy postmenopausal women recruited from the general community. The mean age was 66.41 ± 4.82 years, range 60–79. Total body composition (fat and lean tissue) and regional bone density in the lumbar spine and femur were measured by dual energy X-ray absorptiometry (DXA) on a Lunar DPX-IQ. The participants were screened for medical conditions that may alter BMD, and were excluded from the study if they had been on hormone-replacement therapy (HRT). Contraindications also included: cigarette smoking and alcohol abuse. The relationship of BM, FM and FFM with BMD were first generated separately using linear regression (bivariate). Multiple linear regression then was used to determine the relative contribution of BM, FM and FFM to the variance in BMD. RESULTS: Total BM was more strongly correlated with femur and lumbar spine BMD (r = 0.54 and 0.37, respectively) than FM (r = 0.30 and 0.19) and FFM (r = 0.44 and 0.26). CONCLUSION: Both fat and lean tissue mass are related to femur bone mass in postmenopausal women, however the relationship being strongest for body weight. FM shows weaker correlations for both femur and lumbar BMD. In view of the direction and magnitude of changes in body composition and bone mineral after the menopause, body weight and muscularity are more likely to be determinants of peak bone mass of postmenopausal Brazilian women.