Measurement of Total Bodywater Volume with Deuterated Water in Newborn Infants

Abstract

D₂O and H₂¹⁸O are often used as tracers for the determination of total body water (TBW). For newborn infants, the commonly used noninvasive method has not been validated. In this study TBW was calculated from D₂O concentrations in blood and compared with TBW calculated from D₂O concentrations in urine. TBW calculated from all urine portions voided at least 6 h after D₂O administration on average was 1.0% lower. TBW calculated from only three urine portions voided 6, 12, and 24 h after D₂O administration was 0.6% (mean) lower compared to TBW calculated from D₂O concentrations in blood. This study indicates that the noninvasive method to measure TBW can be considered a reliable method when used in newborn infants.