Relation of forearm's bone and soft tissues to infant's body composition.

Abstract

Small portable units using the dual X-ray absorptiometry method (pDEXA) are becoming available to evaluate a localized region of the body such as the forearm. The purpose of this study was to evaluate the relationship between infant's forearm measurements of bone mineral, lean, and fat mass and total body composition. Twenty-two infants participated in this study. Mean age of the infants was 21 d with a weight range of 1-3.6 kg. All infants were stable and had their forearm and total body scanned on the same day. The long-term precision error for the pDEXA was 0.4%. The infant's total body was scanned by the XR-26 (Norland Medical Systems, Fort Atkinson,WI). Forearm bone mineral content, bone mineral density (BMD), fat mass, and lean mass correlated to total body mineral content (BMC) (r = 0.84, p < 0.001), total body BMD (r = 0.73, p < 0.001), total fat mass (r = 0.53, p < 0.05), and total body lean mass (r = 0.80, p < 0.001). Forearm BMC, lean, and fat mass correlated significantly with body weight and length (r = 0.73-0.94). In conclusion, forearm measurements of bone mineral, fat, and lean mass reflect total body bone mineral, fat, and lean mass in small infants.