de Lorenzo A, Sorge S P, Iacopino L, Andreoli A, de Luca P P, Sasso G F
Department of Biomedical Sciences, University Tor Vergata, Rome, Italy.
Appl Radiat Isot. 1998 May-Jun;49(5-6):739-41. doi: 10.1016/s0969-8043(97)00099-7.
Body composition (BC) assessment is a useful tool for a careful evaluation of nutrition status. Bioelectrical impedance analysis (BIA) is a safe, low-cost and reliable method for BC assessment. For epidemiological and clinical research in children, paediatric-age specific formula for fat-free mass (FFM) prediction from BIA is needed. Thus, in 35 children (age 7.7-13.0 years) with different levels of body fatness (relative weight for age 70.6-133.8%), FFM was calculated from dual-energy X-ray absorptiometry (DXA). A regression equation from BIA and DXA data was elaborated. The impedance index (ZI = height2/bioelectrical impedance) was the strongest predictor of FFM, explaining 89% of its variance. However, the variance increased to 96% when body weight was added with ZI in the regression model. No variable, including sex and age, contributed to the prediction of FFM in the presence of ZI and body weight. The regression formula [FFM = 2.330 + 0.588 ZI (cm2/omega) + 0.211 Weight (kg) (r = 0.96, SEE = 1.0 kg)], allows a reliable prediction of FFM in children from body impedance values.
身体成分（BC）评估是仔细评估营养状况的一项有用工具。生物电阻抗分析（BIA）是一种用于BC评估的安全、低成本且可靠的方法。对于儿童的流行病学和临床研究，需要有根据BIA预测无脂肪量（FFM）的特定儿科年龄公式。因此，在35名年龄7.7 - 13.0岁、身体脂肪水平不同（年龄相对体重70.6 - 133.8%）的儿童中，通过双能X线吸收法（DXA）计算FFM。根据BIA和DXA数据构建了一个回归方程。阻抗指数（ZI = 身高²/生物电阻抗）是FFM的最强预测因子，可解释其89%的方差。然而，当在回归模型中加入体重与ZI时，方差增加到96%。在存在ZI和体重的情况下，包括性别和年龄在内的任何变量对FFM的预测均无贡献。回归公式[FFM = 2.330 + 0.588 ZI（cm²/欧姆）+ 0.211体重（kg）（r = 0.96，SEE = 1.0 kg）]，可根据身体阻抗值对儿童的FFM进行可靠预测。
