Comparison of techniques to estimate total body skeletal muscle mass in people of different age groups
Comparison of techniques to estimate total body skeletal muscle mass in people of different age groups
复制标题
DOI：
10.1152/ajpendo.1999.277.3.e489
复制
发表时间：
1999-09-01
影响因子：
5.1
通讯作者：
Nair, KS
中科院分区：
文献类型：
--
作者：
Proctor, DN;O'Brien, PC;Nair, KS
在59名健康男性和女性[20-30岁（年轻），45-59岁（中年）和60-79岁（老年）]中，将双能X线吸收测定法（DXA;胸肌质量除以0.75）估计的全身肌肉质量与24小时尿肌酐排泄量进行比较，这些男性和女性在临床研究中心停留5天。还测量了全身水分（（H2O）-H-2稀释）、脂肪（水下称重）、骨矿物质（DXA）和全身蛋白质质量（基于4室模型）。DXA和肌酐的肌肉质量估计值高度相关（r = 0.80）。然而，逐步多元回归表明，在基于DXA的肌肉质量估计中，受试者之间的显著差异可以用全身水分来解释。肌酐排泄、膝伸肌力量和全身蛋白质质量均随年龄增长而下降，表明肌肉细胞质量随年龄增长而下降。然而，基于DXA的肌肉质量和非脂肪体重的测量（即，通过（H2O）-H-2测定的瘦体重和通过水下称重测定的去脂体重）不随年龄变化。这些结果表明，DXA.和尿肌酸酐排泄量对全身肌肉质量随着衰老的下降给出了不同的结果。DXA明显低估年龄相关性肌肉减少症的因素仍有待充分确定，但体内水分的变化可能是一个重要的贡献者。
An estimate of total body muscle mass with dual-energy X-ray absorptiometry (DXA; appendicular muscle mass divided by 0.75) was compared with 24-h urinary creatinine excretion in 59 healthy men and women [20-30 yr (younger), 45-59 yr (middle age), and 60-79 yr (older)] who stayed in a clinical research center for 5 days. Total body water ((H2O)-H-2 dilution), fat (underwater weighing), bone mineral (DXA), and total body protein mass (based on a 4-compartment model) were also measured. Muscle mass estimates by DXA and creatinine were highly correlated (r = 0.80). However, stepwise multiple regression indicated that a significant amount of additional between-subject variability in DXA-based muscle mass estimates could be explained by total body water. Creatinine excretion, knee extensor strength, and total body protein mass all decreased with age, suggesting a decline in muscle cell mass with aging. However, DXA-based muscle mass and measures of nonfat body mass (i.e., lean body mass by (H2O)-H-2 and fat-free body mass by underwater weighing) did not change with age. These results indicate that DXA. and urinary creatinine excretion give different results regarding the decline in total body muscle mass with aging. The factor(s) responsible for the apparent underestimate of age-related sarcopenia by DXA remain to be fully defined, but changes in body water may be an important contributor.