Assessment of serum 25(OH)D level in infants with bronchiolitis

Bronchiolitis is one of the most common diseases of the lower respiratory tract in infants. Vitamin D has been shown to be protective against lower respiratory infections; however, there are limited and contradictory results in relation to serum vitamin D level and the incidence of bronchiolitis in children. The aim of this study was to compare serum levels of this vitamin in healthy infants and infants with acute bronchiolitis.
This case-control study conducted at Abuzar hospital in Ahvaz city, during October to March of 2014. Three groups of 45 eligible infants including control, low and high intensity of bronchiolitis enrolled to study. The severity of bronchiolitis classified according to scores derived from the respiratory distress assessment index. One to eight scores considered as low intensity and 9 to 17 scores considered as high intensity of bronchiolitis. Subsequently, 3 ml of venous blood sample were taken from them and the serum levels of 25(OH)D were measured by using an enzymatic kit.
60 (44.4%) infants were girls. The mean age of the control, low and high intensity of bronchiolitis groups were 11.2±5.2, 10±5.8 and 9.8±4.7 months, respectively (P=0.1). The mean of 25(OH)D concentrations in the control, low and high intensity bronchiolitis groups were 28.3±19.4, 17.7±11.7 and 13.6±5.7 nm/l, respectively. There was a significant difference in levels of 25(OH)D between the control-low intensity bronchiolitis groups (P=0.001) and the control-high intensity bronchiolitis groups (P=0.002), this difference was not significant between the two groups of bronchiolitis. There was a direct and significant correlation between serum level of 25(OH)D and age (r=0.2, P=0.005), breast milk consumption (r=0.3, P=0.001), and vitamin D supplementation (r=0.6, P=0.000).
In the present study, levels of 25(OH)D were significantly lower in infants with bronchiolitis than control group. In addition, 25(OH)D levels did not affect the severity of bronchiolitis.