Serum Vitamin D Levels in Asthmatic Children and Adolescents and Its Relationship with Asthma Control

Background: This study aimed to investigate serum 25-hydroxyvitamin D levels in children with asthma and evaluate its association with clinical and laboratory features of asthma, as well as asthma control status.Materials and Methods: Eighty-one asthmatic children (35 girls, 46 boys), aged between 5 and 18 years, who were followed at the Pediatric Allergy Outpatient Clinic, were included. Clinical characteristics, family history of atopy, allergy skin prick test results, pulmonary function test parameters, serum total IgE levels, and peripheral eosinophil percentages were retrospectively obtained from medical records. Asthma control status assessed by both physicians and patients. Blood samples were obtained from all children for the measurement of vitamin D levels. Patients were grouped according to serum vitamin D levels, asthma control status, and treatment regimens.Results: The mean serum vitamin D level was 17.9 ± 8.3 ng/mL. Of the patients, one (1.2%) had severe vitamin D deficiency (<5 ng/mL); 32 (39.5%) had deficiency (serum vitamin D levels of 5-15 ng/mL); and 19 (23.5%) had insufficiency (serum vitamin D levels of 15-20 ng/mL). Serum vitamin D levels were sufficient (>20 ng/mL) in 29 (35.8%) patients. No significant relationship was found between serum vitamin D levels and total IgE levels, eosinophil percentages, allergy skin prick test results, or treatment regimens. Similarly, there was no statistically significant association between serum vitamin D levels and asthma control status assessed by either the physician or the patients and their parents. However, vitamin D deficiency was significantly associated with experiencing more than one asthma attack in the past year (p = 0.05).Conclusion: More than half of the asthmatic children included in the study had vitamin D deficiency or insufficiency. Although serum vitamin D levels were not significantly associated with asthma control status, lower levels were linked to an increased risk of frequent asthma attacks.