REFERENCE VALUES OF BODY-COMPOSITION OBTAINED BY DUAL-ENERGY X-RAY ABSORPTIOMETRY IN PRETERM AND TERM NEONATES

Background: As previously reported, dual-energy x-ray absorptiometry p rovides reliable and accurate values for bone mineralization in piglet s and infants, but overestimates fat content in small infants. The pur pose of the current study was to determine an appropriate equation of correction for fat mass measurement and to establish reference values of body composition of preterm and term neonates. Methods: Fat mass an d chemical whole-body fat content were evaluated by dual-energy x-ray absorptiometry in eight piglets with a body weight between 1408 and 51 51 g. The results were combined with previous data obtained in 13 pigl ets, and two correction equations were determined according to fat mas s content. Close to birth, 106 healthy appropriate-for-gestational age preterm and term infants were scanned by dual-energy x-ray absorptiom etry to determine bone mineral content, bone area, and fat mass. Fat m ass content determined by dual-energy x-ray absorptiometry was correct ed using the equations obtained in piglets after which lean body mass was recalculated. Results: Multivariate analysis showed that dual-ener gy x-ray absorptiometry body weight was the best predictor of bone min eral content(r(2) = 0.94), bone area(r(2) = 0.95), lean body mass (r(2 ) = 0.98), and fat mass (r(2) = 0.84). Gender was an additional signif icant independent variable for fat mass and lean body mass. Body weigh t related curves of percentiles for bone mineral content, bone area, f at mass, and lean body mass, were constructed. In vivo dual-energy x-r ay absorptiometry values of fat mass and calcium content estimated fro m bone mineral content were in accordance with previously reported who le-body carcass reference values in preterm and term neonates. Conclus ion: Normative data of dual-energy x-ray absorptiometry body compositi on for healthy preterm and term infants are provided and can therefore be used in research and in clinical practice.