Does Vitamin D Have a Role in the Inception of Childhood Asthma? - A Comparative Cross-Sectional Study

BACKGROUND Global prevalence of paediatric asthma has shown a sharp increase in last three decades. Recently vitamin D has been linked with lung function and vitamin D supplementation can lessen the acute exacerbations in asthmatic children. The purpose of the study was to compare lung parameters and vitamin D levels in asthmatic and non-asthmatic children and assess the correlation between vitamin D levels and pulmonary function parameters in children. METHODS A cross-sectional study was conducted among 40 asthmatic children and 42 healthy volunteers between the age group of 5 and 18 years attending the paediatric outpatient department (OPD) in a tertiary care centre in Coimbatore. Pulmonary functions were assessed using computerized spirometer and the serum 25-hydroxy vitamin D levels were estimated by Diazyme EZ vitamin D assay latex enhanced immunoturbidimetric method. The results were compared between asthmatics and non-asthmatics to find out the association. RESULTS The average age of the study participants was 10.5 ± 2.5 years. Lung parameters and mean vitamin D levels are reduced in asthmatics. There is a positive significant correlation between serum vitamin D levels and forced expiratory volume FEV1 / forced vital capacity (FVC) (P < 0.05, r = 0.781), and also between vitamin D and FEV1 (P < 0.05, r = 0.28). Lung parameters like FEV1, FEV1 / FVC ratio and peak expiratory flow rate (PEFR) are significantly decreased in asthmatic children. CONCLUSIONS Majority of the asthmatics have insufficient vitamin D levels than the normal peers with no asthma. Our study confirms the positive association between vitamin D and FEV1 and FEV1 / FVC ratio. KEYWORDS Vitamin D, Asthma, Pulmonary Function, Lung Parameters