Causes and Consequences of Sodium Imbalances in the First Week of Life in Very Low-Birthweight Infants

Abstract

Abstract Background: Sodium imbalance is common in the first week of life in very low-birthweight infants (VLBWI) and may be associated with poor outcome. Objective: To determine the incidence and outcomes of both hypo- and hypernatraemia in VLBWI (500–1500 g birthweight) in the first week of life. Methods: This was a retrospective cross-sectional descriptive study evaluating sodium abnormalities in VLBWI in the first week of life. Subjects included all VLBWI born at Charlotte Maxeke Johannesburg Academic Hospital between 1 January 2013 and 31 July 2013. The causes and complications associated with sodium abnormalities and their outcomes were reviewed. Results: Sodium imbalances were found in 29.1% (85/292) VLBWI. Hypernatraemia was present in 27.1% (79/292) and hyponatraemia in 2.0% (6/292). There was no difference in birthweight or gestational age between hyponatraemic and hypernatraemic VLBWI. Within the hypernatraemic VLBWI, mortality was significantly increased in much smaller and more preterm infants (p < 0.001) and in infants with higher sodium levels (p < 0.005). The main causes of hypernatraemia were insensible water loss through the skin (73.9% of babies born via normal vaginal delivery) and respiratory system (60% of babies were on continuous positive airway pressure (CPAP)). Conclusion: Hypernatraemia is common in the first week of life in VLBWI. Prevention of prematurity and measures to prevent sodium abnormalities should be implemented at birth, especially in very small preterm infants to decrease the mortality and morbidity.