STABLE ISOTOPES AND BIOELECTRICAL-IMPEDANCE FOR MEASURING BODY-COMPOSITION IN INFANTS BORN SMALL-FOR-GESTATIONAL-AGE

The assessment of body composition in infants born small for gestation al age (SGA) is required primarily to evaluate nutritional status and to monitor growth in the neonatal period. Measurement of total body wa ter, using stable isotopes of hydrogen (H-2) and oxygen (O-18), offers a potential method by which body composition can be assessed. This te chnique is non-invasive and recently has been used successfully in a c ohort of 5-week-old infants born SGA. Nevertheless, the assessment of total body water using stable isotopes requires specialized laboratori es and equipment, which may limit its use. Prediction of total body wa ter by bioelectrical impedance is a possible alternative. This techniq ue uses electrical theory to predict the volume of the conducting medi um in the body, namely, water. A potential limitation of bioelectrical impedance analysis is the accuracy, which may impinge on its usefulne ss in small infants.