title: The relationship between serum 25 hydroxy vitamin d levels and asthma in children.
abstract: OBJECTIVE
  Asthma and other allergic disorders have increased over the past decades in nearly all nations. Many studies have suggested the role of vitamin D deficiency in both T-helper1 and T-helper2 diseases; however, the association between vitamin D, allergy, and asthma remains uncertain. In this study, the associations of 25-hydroxy vitamin D3 levels with asthma and with the severity of asthma were evaluated.
  
  
  METHODS
  This cross-sectional study was conducted on 50 asthmatic children and 50 healthy controls aged 6-18 years. Serum 25-hydroxy vitamin D3 levels were determined and compared between the two groups. The relationship between serum vitamin D levels and pulmonary function test outcomes and eosinophil counts were examined in asthmatic patients.
  
  
  RESULTS
  Univariate analysis of the relationship between asthma and vitamin D showed that decreased vitamin D levels were associated with significantly increased odds of asthmatic state (P=0.002). In a multivariate analysis after adjustment for age, body mass index, and sex, the relationship between vitamin D and asthma increased. In asthmatic patients, 25-hydroxy vitamin D levels had direct and significant correlations with both predicted FEV1 (R(2)=0.318; P=0.024) and FEV1/FVC (R(2)=0.315; P=0.026). There were no associations between vitamin D level and eosinophil counts, duration of disease, and the number of hospitalization or unscheduled visits in the previous year (P>0.05).
  
  
  CONCLUSIONS
  These results showed that serum 25-hydroxy vitamin D levels were inversely associated with asthma, and there was a direct and significant relationship between vitamin D levels and pulmonary function test outcomes in asthmatic children. An interventional study in asthmatic patients with low serum vitamin D concentration may establish a causal relationship between asthma and vitamin D.
authors.affiliation: Division of Allergy and Immunology, Department of Pediatrics, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Soheila
authors.initials: S
authors.lastname: Alyasin
authors.forename: Tooba
authors.initials: T
authors.lastname: Momen
authors.forename: Sara
authors.initials: S
authors.lastname: Kashef
authors.forename: Abbass
authors.initials: A
authors.lastname: Alipour
authors.forename: Reza
authors.initials: R
authors.lastname: Amin