[Association of vitamin D concentrations with juvenile idiopathic arthritis]

25-Hydroxyvitamin D3 [25(OH)D3] is the main product of vitamin D and can reflect the absolute concentration of active vitamin D in the body. This study examined serum 25(OH)D3 levels in children with juvenile idiopathic arthritis (JIA) in order to explore the association of vitamin D concentrations with the pathogenesis and disease activity of JIA.

Serum samples were collected from 53 children confirmed as having JIA between January 2013 and March 2014, as well as 106 healthy children (control group) who underwent physical examination in the same period. Serum concentrations of 25(OH)D3 were measured using ELISA and compared between the cases and healthy controls. The association of serum 25(OH)D3 levels with JIA subtypes, ACR Pediatric 30 Score, peripheral blood C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were analyzed in children with JIA.

Compared with the control group, the JIA group had significantly reduced serum 25(OH)D3 levels (median: 42.6 nmol/L vs 49.9 nmol/L; P<0.01). The percentage of subjects with severe deficiency of vitamin D in the JIA group was significantly higher than that in the control group (17.0% vs 6.6%; P<0.05). Serum 25(OH)D3 showed no significant correlations with JIA subtypes, ACR Pediatric 30 Score, CRP, and ESR in children with JIA.

Vitamin D concentrations are significantly decreased in children with JIA. Decreased vitamin D concentrations may be associated with the pathogenesis of JIA. However, vitamin D concentrations may have no correlations with JIA subtypes, disease severity, and disease activity.