Abstract
Vitamin D deficiency is common and widespread globally. Vitamin D has an immunomodulatory effect, but it is still unclear whether its deficiency is associated with higher disease activity. The aim of this retrospective study was to determine the serum concentration of vitamin D in children with paediatric arthritis (juvenile idiopathic arthritis and reactive arthritis). Prevalence of hypo-vitaminosis D among 98 children with juvenile idiopathic arthritis and reactive arthritis was determined and association between serum concentration of vitamin D and disease activity markers was found. Prevalence of vitamin D deficiency among children included in this study was 69.07%. Children with juvenile idiopathic arthritis had a significantly lower vitamin D level than children with reactive arthritis. There was a statistically significant moderate negative correlation between serum concentration of vitamin D and patient age, as well as a weak negative correlation between vitamin D level and patient body mass index. The significant correlations found between vitamin D level and inflammatory markers indicate that further research on the role of vitamin D in disease activity is needed.