The Relationship between Bronchiolitis Severity and Vitamin D Status

Background/Aim: Acute bronchiolitis is mostly caused by viral agents in children under 2 years of age. The disease mostly has a mild clinical course however severe cases are not uncommon. Vitamin D is known to exert immune-regulatory functions. We aimed to examine the association between the clinical severity of acute bronchiolitis and serum vitamin D levels in infants. Materials and methods: A total of 182 children with acute bronchiolitis were prospectively enrolled. The disease severity was assessed using the Modified Tal Scoring System and their vitamin D levels were evaluated. Results: Vitamin D deficiency or insufficiency was as high as 47.8% in infants with bronchiolitis. Infants with low vitamin D levels comprised a significantly larger proportion of patients with severe bronchiolitis (p = 0.002). Infants admitted to intensive care unit had significantly higher degrees of vitamin D deficiency or insufficiency (p < 0.001). Conclusion: Vitamin D deficiency is closely linked with severe bronchiolitis and the need for intensive care unit admission in infants. We believe that assessment of vitamin D levels in infants prior to bronchiolitis season and appropriate supplementation may have a protective effect against severe bronchiolitis.