Etiology and Outcomes of Hypernatremia in a Tertiary Pediatric Intensive Care Unit: The Role of Disease Severity

Purpose: Hypernatremia is a common electrolyte disorder in pediatric intensive care units (PICU) and is associated with considerable morbidity and mortality. We aimed to evaluate underlying etiologies, clinical characteristics, and factors associated with outcomes in critically ill children with hypernatremia, while accounting for illness severity. Methods: We retrospectively analyzed pediatric patients with at least one serum sodium measurement > 145 mEq/L during their stay in a tertiary Level 3 PICU. Demographic, clinical, laboratory, Glasgow Coma Scale (GCS), and Pediatric Risk of Mortality (PRISM) data were collected. Factors associated with in-hospital mortality were evaluated using univariate and multivariable analyses. Results: A total of 113 children were included (mean age 4.8 ± 5.3 years; 57.5% male). Neurological disorders were the most common underlying disease category, while free water deficit was the most frequently identified etiology of hypernatremia. Overall in-hospital mortality was 15.9%. Mortality rates were 21.5% among patients with PICU-associated hypernatremia and 8.3% among those with hypernatremia within the first 24 h of admission; the difference was not statistically significant (p = 0.058). PRISM score remained independently associated with mortality (OR 1.124, 95% CI 1.059–1.193; p < 0.001), whereas serum sodium concentration was not significantly different between survivors and non-survivors. Conclusions: Among critically ill children with hypernatremia, mortality was higher than the overall PICU mortality rate but was primarily associated with overall illness severity rather than with the degree of hypernatremia itself. PRISM score, rather than serum sodium concentration, was independently associated with mortality, suggesting that hypernatremia may represent a marker of severe underlying illness rather than an independent determinant of outcome.