VALIDATION AND APPLICATION OF DUAL-ENERGY X-RAY ABSORPTIOMETRY TO MEASURE BONE MASS AND BODY-COMPOSITION IN SMALL INFANTS

Precision and validity of dual-energy x-ray absorptiometry (DXA) for a nalysis of whole-body composition in infants were assessed by 1) scann ing piglets in triplicate to calculate CVs, and 2) comparing DXA estim ates with chemical analysis of whole carcass. The mean CVs for all DXA measures in small piglets and large piglets were < 2.5%, except for f at mass, which were 6.3% and 3.5%, respectively. In large piglets DXA provided reasonable estimates of chemical analysis for bone mineral co ntent (BMC), lean body mass, and fat mass, but only for lean body mass in small piglets. DXA overestimated fat by twofold and underestimated BMC by a third in small piglets. Scans of prematurely born infants (n = 17) at term and at 3, 6, and 12 mo corrected age demonstrated that changes in BMC, lean body mass, and fat mass can be quantitated by DXA . However, further refinement of DXA technology is necessary before re liable measures of BMC and fat mass in small infants are attainable.