Low serum 25-hydroxyvitamin D levels and bronchiolitis severity in Spanish infants

This cross-sectional study was performed to examine the prevalence of hypovitaminosis D in infants with acute bronchiolitis compared with control subjects and to evaluate the relationship between serum 25-hydroxyvitamin D (25(OH) D) and the severity of bronchiolitis. Serum 25(OH) D levels were measured by radioimmunoassay in 48 infants with acute bronchiolitis (2.5 ± 2.0 months) and in 30 healthy infants (3.2 ± 2.3 months). 25(OH) D levels (ng/ml) in children with acute bronchiolitis were significantly lower than in the control group (median 29.9 ng/ml (interquartile range (IQR) 21.4–37.5) versus median 38.2 ng/ml ((IQR 26.1–48.1), p = 0.022), mainly in infants with moderate–severe bronchiolitis (median 29.8 ng/ml, IQR 19.2–35.9). The prevalence of hypovitaminosis D was remarkably greater among infants with bronchiolitis than in control subjects (52.1 versus 26.6 %). A significant inverse correlation was found between serum 25-hydroxyvitamin D levels and disease severity (rho = −0.457, p < 0.001).