The prevalence of hyponatremia and effects of aminophylline on serum sodium ions in premature neonates admitted to Neonatal Intensive Care Unit, at the University Teaching Hospital, Lusaka, Zambia

Abstract

BACKGROUND: Hyponatremia, defined as serum sodium less than 135mmol/l, is a very common disorder in neonates. It accounts for about 30% of hospitalised cases worldwide, especially in premature neonates admitted to an intensive care unit. The overall morbidity and mortality from hyponatremia worldwide is reported to be at 42%. Studies done in adults and neonates have demonstrated that aminophylline, an adenosine A1 receptor antagonist, has a diuretic effect and has been implicated in lowering serum sodium levels in premature neonates. However these studies did not address the need for sodium supplementation for neonates receiving aminophylline. This study aimed at determining the prevalence of hyponatremia in premature neonates, and the effects of aminophylline administration on serum sodium levels in Neonatal Intensive Care Unit (NICU) at the University Teaching Hospital (UTH). METHOD: A cross sectional study design was employed to study 322 premature neonates who were enrolled between October 2013 and February 2014. The mean weight and mean gestational age of the participants was 1.44kg and 31.85 weeks respectively. Out of the 322 participants 188 met the criteria for aminophylline administration and were given a loading dose. As part of routine management, blood samples were collected on admission and 12hours after a loading dose of aminophylline. The blood samples were taken to UTH paediatrics laboratory for analysis. The analysis involved measuring the serum sodium levels using Pentra C400. RESULTS: According to the findings, this study shows that in premature neonates the prevalence of hyponatremia in NICU at UTH is 51%. The study further established that the majority of the premature neonates showed a significant decrease in serum sodium levels after taking a loading dose of aminophylline with P-value 0.0000. Among the factors that the study looked at, weight and gestational age, were significantly associated with hyponatremia with P-values 0.041 and 0.009 respectively. CONCLUSION: The prevalence of hyponatremia in NICU at UTH is significantly high and using aminophylline in premature neonates lowers serum sodium levels and sodium supplements may be required. Among the factors that the study looked at, only weight and gestational age were significantly associated with hyponatremia in premature neonates admitted to NICU at UTH. Nevertheless, the renal actions of aminophylline in premature neonates merit further investigation.