CROSS-CALIBRATION OF BODY-COMPOSITION TECHNIQUES AGAINST DUAL-ENERGY X-RAY ABSORPTIOMETRY IN YOUNG-CHILDREN

Using dual-energy X-ray absorptiometry (DXA) as a standard method for determining body composition in children, we evaluated the accuracy of skinfold-thickness measurements (with the Slaughter et al equations, which are based on triceps and calf skinfold-thickness measurements), bioelectrical resistance (BR; with the Kushner et al equations and age -specific hydration constants), and other clinical measurements (indiv idual skinfold thicknesses and body mass index) for the assessment of body fat in children. We studied a heterogenous group of 49 boys and 4 9 girls, aged 6.6 +/- 1.4 y and weighing 24.1 +/- 5.9 kg. Fat mass est imated by DXA was significantly lower than fat mass measured by skinfo ld thickness, even though fat mass measurements by these two technique s were strongly related to each other. Fat mass estimated by DXA was a lso significantly lower than fat mass measured by BR, and the model R( 2) and SEE were not as strong as for the skinfold-thickness technique. Fat mass estimated by DXA also correlated with other clinical indexes such as triceps skinfold thickness, body mass index, body weight, and subscapular skinfold thickness. In forward-regression analysis, subsc apular skinfold thickness, body weight, triceps skinfold thickness, se x, and height(2)/resistance estimated the value for fat mass measured by DXA with a model R(2) Of 0.91 and an SEE of 0.94 kg fat mass. These studies suggest that existing techniques for assessing body fat in ch ildren may be inaccurate. We provide new anthropometric equations base d on the use of DXA as a criterion that provide accurate and precise m easures of body fat and fat-free mass in white children aged 4-9 y. Th is approach provides estimates of body fat standardized to a known lab oratory standard of chemical analysis of carcasses.