Modifications in the spectrum of bone mass predictive factors with menopausal status

Fat mass (FM) is a source of adipocytokines, with both positive and negative bone consequences. We aimed to investigate the role of body composition and adipokines as predictive factors for bone mass in women.

This cross-sectional study included 93 women (38 premenopausal and 55 postmenopausal). Bone mineral density (BMD) and body composition were assessed by dual-energy X-ray absorptiometry. Serum levels of leptin, adiponectin, resistin, and also of the phosphocalcic markers parathormone and vitamin D were measured.

Only lean mass (LM) was an independent predictor of BMD in premenopausal women (r² = 0.381, p < 0.001 for femoral neck BMD, r² = 0.2, p < 0.01 for whole-body BMD) in both unadjusted and age-adjusted models. The effect of total FM upon BMD became nonsignificant when LM was added to the models assessed. In postmenopausal women, although LM, trunk-to-leg fat ratio, and resistin were initially associated with BMD in unadjusted models, only the trunk-to-leg fat ratio independently predicted BMD at various sites (r² = 0.171, p < 0.01 for lumbar BMD, r² = 0.078, p < 0.05 for radius BMD, r² = 0.094, p < 0.05 for whole-body BMD) after adjusting for age.

While in premenopausal women the effect of LM upon bone is prevalent, after menopause, the fat distribution reflected by trunk-to-leg fat ratio is a major determinant of bone mass at different sites. Our study also stresses that the relationship between total FM and BMD is not mediated by adipokines in women irrespective of menopausal status and body composition, but it is largely mediated by LM only in young premenopausal women.