OBJECTIVETo study the changes in the serum levels of 25-(OH)D3 and immunoglobulins in children with bronchiolitis, and the clinical significance of these changes.

METHODSSerum levels of 25-(OH)D3 were measured using ELISA in 35 children with bronchiolitis in the acute and recovery phases and 20 healthy children. Serum levels of immunoglobulins were determined by rate nephelometry.

RESULTSCompared with the healthy children, serum 25-(OH)D3, IgG and IgA levels in children with bronchiolitis in the acute phase were significantly lower and, in contrast, serum IgE levels were significantly higher (P<0.05). Serum 25-(OH)D3 levels increased and serum IgE levels decreased significantly in the recovery phase compared with the acute phase in children with bronchiolitis (P<0.05). However, compared with the healthy children, serum 25-(OH)D3 and IgA levels were significantly lower and serum IgE levels were significantly higher in children with bronchiolitis in the recovery phase (P<0.05). Serum 25-(OH)D3 levels in children with bronchiolitis in the acute phase were positively correlated with serum IgG (r=0.36, P<0.05) and IgA levels (r=0.63, P<0.01), and negatively correlated with serum IgE levels (r=-0.72, P<0.01). A negative correlation was found between serum 25-(OH)D3 and IgE levels in children with bronchiolitis in the recovery phase (r=-0.34, P<0.05).

CONCLUSIONSSerum 25-(OH)D3 levels decrease and there is immunoglobulin level imbalance in children with bronchiolitis, suggesting that 25-(OH)D3 and immunoglobulins may play important roles in the pathogenesis of bronchiolitis.