Assessment Of Vitamin D Role In The Pathogenesis Of Asthma In Vitamin D Resistent Patients

Research Title: Evaluation of airway reactivity, allergy and inflammatory mediators in exhaled breath condensate in vitamin D resistant rickets. Introduction: Vitamin D seems to play a role in allergic and asthmatic reactions. Vitamin D resistant rickets patients lack vitamin D receptors and cannot absorb vitamin D. Aim: To assess the effect of absence of vitamin D receptors on airway reactivity, allergy and inflammatory mediators in exhaled breath condensate. Design: Prospective study evaluating these parameters in patients with vitamin D resistant rickets and in healthy controls. Participant selection: The study group will consist of vitamin D resistant rickets patients followed and treated at the Pediatric Endocrinology Department at our hospital. The study group will be compared to an age- and sex-matched healthy control group that had a negative methacholine challenge test. Sample size: 40 participants in the two groups. Intervention: Each subject will undergo evaluation including a respiratory questionnaire, pulmonary function tests, methacholine challenge test with determination of PC20, exhaled nitric oxide (eNO), and exhaled breath condensate (EBC). Venous blood will be analyzed for complete blood count + eosinophils, IGE levels, and Vitamin D levels. Prick skin test for inhaled allergens will be performed. All measurements will be evaluated in a single 3 hour visit, with no follow up study visits. Primary end point: Airway reactivity as assessed by methacholine challenge test. Secondary outcome parameters: All other parameters are the secondary end points.