Wang ZiMian, Zhu Shankuan, Wang Jack, Pierson Richard N, Heymsfield Steven B
Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, USA.
Am J Clin Nutr. 2003 Jan;77(1):76-82. doi: 10.1093/ajcn/77.1.76.
A substantial proportion of total body potassium (TBK) in humans is found in skeletal muscle (SM), thus affording a means of predicting total-body SM from whole-body counter-measured (40)K. There are now > 30 whole-body counters worldwide that have large cross-sectional and longitudinal TBK databases.
We explored 2 SM prediction approaches, one based on the assumption that the ratio of TBK to SM is stable in healthy adults and the other on a multiple regression TBK-SM prediction equation.
Healthy subjects aged >or= 20 y were recruited for body-composition evaluation. TBK and SM were measured by whole-body (40)K counting and multislice magnetic resonance imaging, respectively. A conceptual model with empirically derived data was developed to link TBK and adipose tissue-free SM as the ratio of TBK to SM.
A total of 300 subjects (139 men and 161 women) of various ethnicities with a mean (+/- SD) body mass index (in kg/m(2)) of 25.1 +/- 5.4 met the study entry criteria. The mean conceptual model-derived TBK-SM ratio was 122 mmol/kg, which was comparable to the measurement-derived TBK-SM ratios in men and women (119.9 +/- 6.7 and 118.7 +/- 8.4 mmol/kg, respectively), although the ratio tended to be lower in subjects aged >or= 70 y. A strong linear correlation was observed between TBK and SM (r = 0.98, P < 0.001), with sex, race, and age as small but significant prediction model covariates.
Two different types of prediction models were developed that provide validated approaches for estimating SM mass from (40)K measurements by whole-body counting. These methods afford an opportunity to predict SM mass from TBK data collected in healthy adults.
人体全身钾（TBK）的很大一部分存在于骨骼肌（SM）中，因此提供了一种通过全身计数器测量的（40）K来预测全身SM的方法。目前全球有超过30个全身计数器拥有大量的横断面和纵向TBK数据库。
我们探索了两种SM预测方法，一种基于健康成年人中TBK与SM的比例稳定这一假设，另一种基于多元回归TBK-SM预测方程。
招募年龄≥20岁的健康受试者进行身体成分评估。分别通过全身（40）K计数和多层磁共振成像测量TBK和SM。建立了一个具有经验推导数据的概念模型，将TBK与无脂肪组织的SM联系起来，作为TBK与SM的比例。
共有300名不同种族的受试者（139名男性和161名女性）符合研究纳入标准，其平均（±标准差）体重指数（kg/m²）为25.1±5.4。概念模型推导的平均TBK-SM比例为122 mmol/kg，与男性和女性测量得出的TBK-SM比例（分别为119.9±6.7和118.7±8.4 mmol/kg）相当，尽管在年龄≥70岁的受试者中该比例往往较低。观察到TBK与SM之间存在很强的线性相关性（r = 0.98，P < 0.001），性别、种族和年龄作为虽小但显著的预测模型协变量。
开发了两种不同类型的预测模型，为通过全身计数从（40）K测量值估计SM质量提供了经过验证的方法。这些方法为从健康成年人收集的TBK数据预测SM质量提供了机会。
