Urine Specific Gravity Measurement for Fluid Balance in Neonates on Intravenous Fluids in a Neonatal Intensive Care...

Urine specific gravity reflects hydration status and correlates well with urine osmolality.

To compare intravenous fluid therapy guided with and without inclusion of urine specific gravity to the standard parameters for maintaining postnatal weight loss within permissible limits in neonates admitted to the intensive care unit.

An open-label randomized controlled trial was conducted, including neonates requiring intravenous fluids for ≥72 hours, randomized into the study (urine specific gravity guided fluids) and control arms. The outcomes of the study were to determine proportion of neonates with weight loss within permissible limits, mean percentage weight loss and number of days to reach maximum weight loss.

80 preterm and term neonates (40 in each arm) were enrolled. A comparable proportion of neonates had weight loss within permissible limits in study arm and in control arms [39 (97.5%) vs 36 (90%); P=0.165]. The (mean (SD) percentage weight loss was significantly less in the study arm compared to control arm [All neonates: 7.2(2.6) vs 9.3(3.5); P=0.004); preterm neonates: 7.7 (2.8) vs 11 (3.9); P=0.008)]. Preterm neonates in the study arm attained nadir weight significantly earlier than in the controls (P=0.03) and attained complete enteral feeding earlier. Urine specific gravity showed a moderate negative correlation with the percentage weight loss.

Using urine specific gravity to regulate intravenous fluids in neonates resulted in a significant reduction in postnatal weight loss, especially in preterm neonates.