Association Between Serum Sodium Levels and Clinical Severity of Acute Bronchiolitis in Children: A Cross-Sectional Study

Background: Acute bronchiolitis is a common lower respiratory tract infection in infants and young children and is a frequent cause of hospitalization. Electrolyte imbalance, particularly hyponatremia, may occur during bronchiolitis and could potentially influence disease severity and clinical outcomes. Objective: To assess serum sodium levels in children with acute bronchiolitis and determine their association with the clinical severity of the disease. Methodology: This cross-sectional observational study was conducted in the Department of Paediatrics and Neonatology at Tairunnessa Memorial Medical College & Hospital, Gazipur, from June 2024 to December 2024. Fifty-six children aged 2 months to 2 years with clinically diagnosed acute bronchiolitis were included. Children with congenital heart disease, pneumonia, pulmonary tuberculosis, or acute gastroenteritis were excluded. Blood samples were collected at admission before treatment to measure serum sodium levels. Participants were classified as hyponatremic (<135 mmol/L) or normonatremic (135–145 mmol/L). Disease severity and outcomes were monitored during hospitalization, with p < 0.05 considered statistically significant. Results: Hyponatremia was observed in 12.5% of patients, while 87.5% had normal sodium levels. Disease severity was mild in 37.5%, moderate in 33.9%, and severe in 28.6% of cases. No significant association was found between serum sodium levels and bronchiolitis severity (p > 0.05). No seizures or mortality were reported. Conclusion: Hyponatremia occurred in a small proportion of children with acute bronchiolitis and was not significantly associated with disease severity.