Accuracy of DXA-Based Body Composition Measurements for Pediatric Studies

Abstract

When child growth is examined, measurements should be made of body fat, lean, and mineral composition. Most of the methods available for children, however, are indirect and often rely on constants or calibrations derived from adult measurements. The continued development of one of these techniques, photon absorption, has evolved into the current technology called dual-energy x-ray absorptiometry (DXA). The major advantages of DXA examinations of children are a minimal radiation dose (<1 mrem, whole body), relatively short measurement time (<10 min), and good precision (< 1–2%). The three principal “chemical” components of the whole body reported from a DXA analysis are 1) total bone mineral content (BMC), 2) soft tissue lean mass, and 3) body fat mass. The accuracy of these derived DXA values, however, has never been assessed against classical wet chemistry analyses, especially for children’s body sizes. Thus, the aim of the present study was to assess the accuracy of the absolute mass values of DXA-based body composition measurements.