Lean mass as a determinant of bone mineral density of proximal femur in postmenopausal women

ABSTRACT Objective: To verify which component of body composition (BC) has greater influence on postmenopausal women bone mineral density (BMD). Subjects and methods: Four hundred and thirty women undergoing treatment for osteoporosis and 513 untreated women, except for calcium and vitamin D. Multiple linear regression analysis was performed in order to correlated BMD at lumbar spine (LS), total femur (FT), femoral neck (FN) with body mass (BM), total lean mass (LM) and total fat mass (FM), all determined by DXA. Results: BM significantly correlated with all bone sites in untreated and treated women (r = 0.420 vs 0.277 at LS; r = 0.490 vs 0.418 at FN, r = 0.496 vs 0.414 at FT, respectively). In untreated women, the LM correlated better than FM with all sites, explaining 179% of LS; 32.3% of FN and 30.2% of FT; whereas FM explained 13.2% of LS; 277% of FN, 23.4% of FT In treated women, correlations with BC were less relevant, with the LM explaining 6.7% of BMD at LS; 15.2% of FN, 16% of FT, whereas the FM explained 8.1% of LS; 179% of FN and 176% of FT. Conclusion: LM in untreated women was better predictor of BMD than FM, especialy for distal femur, where it explained more than 30% of the BMD, suggesting that maintaining a healthy muscle mass may contribute to decrease osteoporosis risk. Treatment with anti-osteoporotic drugs seems to mask these relationships. Arch Endocrinol Metab. 2018;62(4):431-7

摘要
研究目的：明确身体成分（BC）的哪一组分对绝经后女性的骨密度（BMD）影响更大。
研究对象与方法：纳入430例接受骨质疏松治疗的女性，以及513名仅补充钙剂与维生素D、未接受其他抗骨质疏松治疗的女性。采用多重线性回归分析，探讨腰椎（LS）、全股骨（FT）及股骨颈（FN）的骨密度与体质量（BM）、总去脂体重（LM）及总脂肪量（FM）的相关性，上述指标均通过双能X线吸收测定法（DXA）检测获得。
结果：体质量与未治疗组及治疗组女性的所有骨密度检测部位均呈显著相关（腰椎相关系数r分别为0.420与0.277；股骨颈r分别为0.490与0.418；全股骨r分别为0.496与0.414）。在未治疗的女性中，去脂体重与各骨部位的相关性优于脂肪量：其对腰椎骨密度的变异解释率为179%，对股骨颈为32.3%，对全股骨为30.2%；而脂肪量对腰椎、股骨颈、全股骨骨密度的变异解释率分别为13.2%、277%与23.4%。在治疗组女性中，身体成分与骨密度的相关性较弱：去脂体重对腰椎、股骨颈、全股骨骨密度的变异解释率分别为6.7%、15.2%与16%，而脂肪量的解释率分别为8.1%、179%与176%。
结论：在未接受治疗的女性中，去脂体重对骨密度的预测效果优于脂肪量，尤其在股骨远端，其对骨密度的变异解释率超过30%，提示维持健康的肌肉量可降低骨质疏松风险。抗骨质疏松药物治疗似乎会掩盖这类相关性。
本文刊载于《内分泌代谢档案》（Arch Endocrinol Metab）2018年；62(4)：431-437。