Serum 25-hydroxyvitamin D levels in children with recurrent wheezing and relation to the phenotypes and frequency of wheezing.

Recurrent wheezing may be related to various reasons. There is a lack of knowledge about the effect of vitamin D status in the children with recurrent wheezing. The aim of this study is to compare the level of vitamin D between recurrent wheezing children and healthy controls, and to investigate the relationship between vitamin D status and the clinical parameters of recurrent wheezing in preschool children. One hundred-ten children followed up in our hospital with recurrent wheezing were included in the study. The control group included fifty children without wheezing episodes. The serum 25-hydroxyvitamin D (25OHD) level was measured. The patients with recurrent wheezing were grouped according to their vitamin D status as "deficient group" and "non-deficient group (Vitamin D level is insufficient and normal)". We investigated the relationship between vitamin D status and the clinical and laboratory parameters of children with recurrent wheezing. Mean 25OHD level was 21.66 ± 8.13 ng/mL (5.6-53) in the study group and 25.36 ± 10.17 ng/mL (6-59) in the control group. The difference was statistically significant (p = 0.015). When the patients with recurrent wheezing were compared according to their vitamin D status, number of hospitalizations, number of positive sensitivity, percentage of eosinophil, serum IgE levels, Asthma Predictive Index positivity and wheezing phenotypes were not found to be different between groups. However, the duration of wheezing, the number of wheezing episodes and systemic glucocorticoid need in the previous year, and the total number of wheezing episodes were significantly higher in the deficient group (p < 0.05). The serum 25OHD level was negatively correlated with the duration of wheezing (r: -0.238; p: 0.012), total number of wheezing episodes (r: -0.436; p: 0.001), number of wheezing episodes in the previous year (r: -0.395; p: 0.001), and systemic glucocorticoid need in the previous year (r: -0.324; p: 0.001). Mean 25OHD levels were lower in patients with recurrent wheezing than in healthy controls. The duration of illness and number of wheezing episodes were correlated with vitamin D levels. An evaluation of the serum levels of vitamin D and supplementation if needed should be recommended in patients with recurrent wheezing, especially in those with long-term and frequent wheezing episodes.