Hyponatremia is a common electrolyte disturbance in critically ill children that has been associated with increased morbidity and mortality. This retrospective, single-center study investigates the prevalence and clinical relevance of hyponatremia at the time of pediatric intensive care unit (PICU) admission, with a particular focus on its association with inflammatory markers and seizures. We conducted a retrospective observational cohort study of pediatric patients beyond the neonatal period who were admitted with hyponatremia (serum sodium ≤ 135 mmol/L) to a German tertiary mixed pediatric and neonatal ICU between January 2015 and October 2024. Among 5,595 admissions screened, 2,906 non-neonatal patients were eligible; 113 presented with hyponatremia upon admission. After excluding cases with type 1 diabetes, chronic diuretic therapy, or hospital-acquired hyponatremia (HAH), 64 patients remained for analysis. Clinical characteristics, inflammatory markers (CRP, IL-6, PCT), and neurological events were evaluated. Among the 64 included children (median serum sodium 129.5 mmol/L), infections were the leading cause of admission. Hyponatremia frequently preceded the rise of inflammatory markers and showed no significant association with CRP, IL-6, or PCT. However, IL-6 and PCT were not routinely measured, limiting interpretability. Length of stay primarily reflected underlying disease severity and showed no correlation with sodium levels. Seizures occurred in 16.4% of patients, although a direct causal link to hyponatremia could not be confirmed. COVID-19–associated hyponatremia was identified in 11 cases, including presentations with pediatric inflammatory multisystem syndrome (PIMS) and encephalopathy. Hyponatremia at PICU admission appears to represent an early indicator of disease burden that is not consistently reflected by conventional inflammatory biomarkers. Its frequent occurrence in infectious and neurological conditions underscores the importance of early recognition and structured interdisciplinary communication across emergency, pediatric, and critical care teams. Prospective studies are needed to validate these findings and delineate disease-specific mechanisms.
Weber et al. (Tue,) studied this question.