Vitamin D levels and vitamin D receptor gene polymorphisms in patients with acute viral bronchiolitis

Objective: Our aim was to investigate the role of vitamin D by comparing vitamin D levels and gene polymorphisms between children with acute viral bronchiolitis and control group. Material and Methods: The study population were recruited from patients admitted to emergency clinic and children and child health clinics of Bulent Ecevit University Training and Research Hospital between June 2012 and June 2013. 54 children hospitalized or ambulatory treated with the diagnose of bronchiolitis and 55 healthy volunteers without a previous history of bronchiolitis between the ages of 1 month and 2 years were included in the study. In both groups, serum 25 (OH) vitamin D levels measured with HPLC and VDR gene Fok I polymorphisms were studied. Pre-natal, post-natal and environmental risk factors which may affect the serum levels of vitamin D were examined. Results: 63% of the study group (n= 34) and 54.5% of control group (n= 30) were male. The median age of the study group was 10.5 (2-24) months and the median age of the control group was 12 (2-23) months. There was no statistically significant difference between the two groups in terms of age. Serum median 25- (OH) vitamin D level of study group was 21.3 (10.7 to 50.5) ng / ml. Serum 25 (OH) vitamin D levels were below 20 ng / ml in 21 cases which was the minimum acceptable level of vitamin D insufficiency. In 6 of these 21 cases, Vitamin D levels were below 15 ng / ml which was considered as vitamin D deficiency. Serum median 25 - (OH) vitamin D level of the control group was 38.1 (25.3 to 61.1) ng / ml. Serum 25 (OH) vitamin D level was statistically significantly lower in the study group than in control group (p <0.001). In both groups, median 25 (OH) vitamin D levels were within normal ranges. Statistically significant difference was detected between bronchiolitis score and serum 25 (OH ) Vitamin D levels (p<0.001). There was no statistically significant difference of Fok I polymorphism of the VDR gene between the study and control group. Conclusion: In our study, lower 25 (OH) vitamin D levels in children with acute viral bronchiolitis suggests that, vitamin D is an important immun modulator and in vitamin D deficiency, the incidence of lower tract infections may increase. Lower vitamin D levels causes more severe bronchiolitis scores. There was no statistically significant difference between Fok I polymorphism and bronchiolitis and serum 25 (OH) vitamin D levels. Key words: Acute bronchiolitis, Vitamin D, VDR gene polymorphism