ABSTRACTS: Oral Presentation Abstracts
Introduction: Preterm neonates are susceptible to metabolic bone disease (hypophosphataemic rickets of prematurity) and compromised nutritional status because of “lost opportunities” from an earlier “exutero” existence and subsequent low calcium and phosphorus intake. We evaluated bone mineral density and body composition using dual-energy X-ray absorptiometry (DXA) within the first 2 weeks of life with the view to establishing norms to correlate with serum biochemical indexes.
Methods: Dual-energy X-ray absorptiometry (DXA) (XR-36; Norland Corporation, Fort Atkinson, WI; small subjects mode) was used to measure bone mineral density and body composition of 15 well preterm neonates. Preterm neonates with birth weight <2500 grams and without multiple congenital anomalies were recruited once they were off oxygen and ventilator support. The neonates were clothed in standard hospital-issued vests and plastic commercial diapers and were sedated for the procedure.
Results: The mean gestation and weight at birth were 32.6 ± 2.1 weeks and 1646 ± 455 g respectively. DXA measurements were made at the mean gestation of 35.1 ± 1.4 weeks and median postnatal age of 16 ± 2.2 days. All the neonates were on a median of 152 ± 7 ml/kg/day feeds (117 ± 6 kcal/kg/day) and had been on feeds for a median of 14 ± 2.4 days. 8 infants were on premature formula alone, 3 on fully-fortified expressed breast milk (FFEBM) alone, 3 on a combination of FFEBM and premature formula and the last infant on a combination of FFEBM and Neosure. The median total body bone mineral density was 0.19 ± 0.05 g/cm2, bone mineral content 36 ± 12.2 g, lean mass 1631 ± 386 g and fat mass 195 ± 113 g. The mean serum biochemical indexes were calcium 2.49 ± 0.08 mM, phosphate 2.2 ± 0.31 mM and alkaline phosphatase 245 ± 83 U/L. None of these neonates required phosphate or vitamin D supplementation.
Conclusion: We hope that these reference values/norms will aid the clinician in preventing or treating rickets of prematurity early. Early intervention may be indicated if sequential DXA scans show a significant drift away from these norms.