Objective To investigate the changing characteristics of muscle mass by dual energy X-ray absorptiometry (DEXA) in middle aged and elderly people with different ages.Methods This study included 343 healthy people aged 50-89 years (178 males and 165 females).Subjects were divided into 4 groups:aged 50-59,60-69,70-79,and 80-89 years group.Fat-free body mass (FFM),the appendicular lean body mass (aLM),trunk lean mass (tLM) were measured by DEXA.The aLM/body weight (Wt％) and aLM index (ASMI) were calculated by DEXA.Results The tLM in both gender was decreased in aged 80-89 years group than in aged 50-59 years group [male (10.6± 1.8) kg vs.(18.4±2.9) kg,female (7.1±1.2) kg vs.(14.8±2.1) kg,F=5.7 and 7.8,P＜ 0.01].The average ASMI in both gender was decreased in aged 70-79 and 80-89 years groups than in aged 50-59 years groups [male (5.5±0.4) kg/m2,(4.9±0.7) kg/m2 vs.(6.1±0.5) kg/m2,female (4.3±0.4) kg/m2,(3.9±0.5) kg/m2 vs.(4.8±0.6) kg/m2,F=24.9 and 9.6,both P＜0.01].The quality of muscle mass was decreased with aging in the elderly.Conclusions Ageing is an important risk factor for sarcopenia in the elderly.DEXA can be used to evaluate the muscle mass in middle aged and the elderly,and ASMI can be used as a reliable measurement index.%目的 应用双能X线吸收法(DXA)观察不同年龄段老年人肌肉质量变化的特点.方法 选取50～89岁人群共343例,其中男性178例,女性165例,将受检人群以10岁为一个年龄段,分成4组,应用Hologic Discovery-Wi型骨密度仪,利用该仪器体成分分析功能,测定去脂体重(FFM),四肢肌肉质量(aLM),躯干肌肉质量(tLM),计算四肢肌肉百分比(Wt％),四肢肌肉质量指数(ASMI). 结果 对不同年龄段老年人的各项DXA检测指标进行分析,80岁组男性下肢肌肉质量为(10.6±1.8)kg,女性下肢肌肉质量为(7.1±1.2)kg,与50岁组比较显著降低(P＜0.01,F=5.7、7.8),70岁组、80岁组的老年人,男性ASMI均值分别为(5.5±0.4) kg/m2、(4.9±0.7) kg/m2,女性ASMI均值分别为(4.3±0.4) kg/m2、(3.9±0.5) kg/m2,和50岁组比较显著降低(P＜0.01,F=24.9、9.6),肌肉质量呈衰减趋势. 结论 增龄是老年肌少症的重要因素,DXA可用于对老年人群肌肉质量的评估,而ASMI可作为可靠的测量指标.
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