DUAL-ENERGY X-RAY ABSORPTIOMETRY STUDIES OF BONE-MINERAL STATUS IN NEWBORN-INFANTS

We studied bone mineral status using dual-energy X-ray absorptiometry (DXA) on 150 singleton newborn infants with birth weights 1002-3990 g and gestational ages (GA) 27-42 weeks. Eighty-five infants were preter m (<38 weeks), and 79 infants were low birth weight (less than or equa l to 2500 g). In addition, we aimed to determine the predictive value of anthropometric measurements, race, and gender on variability in bon e mineral status. Data were acquired using a whole body DXA scanner wi th a pediatric platform. Scan analyses were performed with software ve rsion V5.64P. Results showed a highly significant (p < 0.001 for all c omparisons) correlation among the continuous independent variables, ge stational age, birth weight, study weight, study bare weight, and stud y length, and between independent and each of the dependent variables, total body bone mineral content (TB BMC), TB area, and TB bone minera l density (TB BMD). The best single determinant of bone mineral status is body weight, accounting for 95% of TB BMC and TB area and for 86% of TB BMD variation. Body length was the only additional significant p redictor of TB area. Inclusion of postnatal age (during the first week after birth), race, gender, or season, either individually or in comb ination, failed to improve bone mineral status explanation. By term (G A 38-42 weeks, birth weight 2700-3990 g), the mean TB BMC was 68.2 g, TB area 307.6 cm(2), and TB BMD 0.221 g/cm(2). We conclude that DXA ca n be performed even in small preterm infants during the newborn period . Our results can be used as a basis for further studies in physiologi c and pathologic situations that might affect bone mineralization in i nfants.