Abstract 1102 Poster Session IV, Tuesday, 5/4 (poster 264)

The assessment of bone mineralization, lean, and fat mass is important in neonatology since infants can change their body composition rapidly. However, body composition determination often requires the infant to be transported which may be impossible for many unstable neonates. Smaller, portable units that determine bone mineralization are now available but can only evaluate a localized region of the body such as the forearm. There are few reports about the relation of forearm bone mineral density and soft tissue composition with total body composition. The purpose of this study was to evaluate the performance of a small, portable unit (pDEXA, Norland Medical Systems, Fort Atkinson, WI) that can determine calcium, lean, and fat mass using the dual energy x-ray absorptiometric method (DXA) and to report correlation analyses of forearm measurements of calcium, lean, and fat mass to total body calcium, lean, and fat mass in infants. The pDEXA unit measures 52 cm long, 43 cm wide, and 42.5 cm high and is transportable on a standard hospital cart. Twenty infants from the newborn ICU participated in this study. Mean age of the infants was 21 days old with a weight range of 1 Kg to 2.1 Kg. All infants' total body composition was determined by the XR-26 machine (Norland Medical System) using the DXA method. All infants were clinically stable and had their forearm and total body scanned the same day. The long term precision error for the pDEXA was 0.4%. Forearm bone mineral content, bone mineral density, and lean mass correlated to total body bone mineral content (r=0.79, SEE=8.8 g, P<0.001), bone mineral density (r=0.49, SEE=0.03 g/cm, P<0.05), and lean mass (r=0.95, SEE=29.9 g, P<0.001). There was no correlation with the forearm fat mass and total body fat (r=0.11, NS). Forearm bone mineral content, lean, and fat mass correlated with infants' body weight and length (r=0.68 to 0.88). Only the infants' total body bone mineral content correlated with body weight(r=0.71, P<0.001) and length(r=0.46, P<0.05). In conclusion, a small portable unit using the DXA method can evaluate the infants' forearm bone mineral and lean mass with good correlation with total body measurements. This new portable technology may allow clinicians in the newborn ICU to evaluate body composition changes in infants.