In an attempt to delineate the specific tubular defect in sodium reabsorption in low-birth-weight neonates, fractional sodium excretion [C(Na)/C(Cr)], distal tubular sodium delivery [C(Na)+C(H2O)], and distal tubular sodium reabsorption [C(H2O)/C(H2O)+C(Na)] X 100) were determined in 8 healthy premature and 10 full-term newborn infants. The mean birth weight was 1,701 g (range: 1,240-2,120 g) and the mean gestational age was 32.6 weeks (range: 28-35 weeks) for premature; and 3,199 g (range: 2,670-3,670 g) and 38.9 weeks (range: 38-41 weeks) for full-term neonates. It was demonstrated that the significantly higher fractional sodium excretion in premature infants (1.44 ± 0.33 SE versus 0.36 ± 0.09%, p < 0.01) resulted from significantly decreased proximal ([C(H2O)/H2O)+C(Na)] X 100:69.9 ± 0.105 versus 0.360 ± 0.069 ml/min/1.73 m2, p < 0.05] and distal ([C(H2O)/H2O)+C(Na)] X 100:69.9 ± 3.3 versus 85.8 ± 3.4%, p < 0.01) tubular sodium reabsorption.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Developmental Biology