Is there an association between serum 25-hydroxyvitamin D concentrations and disease activity in rheumatoid arthritis?

BACKGROUND: Recently, it has been recognized that vitamin D not only is important for calcium metabolism and maintenance of bone healthy, but also plays an important role in reducing risk of many chronic diseases including rheumatoid arthritis (RA), systemic lupus erythematosus, insulin-dependent diabetes mellitus, multiple sclerosis, several cancers, heart and infectious diseases. In RA, the role of vitamin D is undefined.

METHODS: The objective of this present study was to determine serum 25-hydroxyvitamin D (25(OH)D) concentrations in patients with RA and to establish its correlation with disease activity. This study was performed on fifty-five consecutive patients RA fulfilling the American Collage of Rheumatology (ACR) criteria for the classification of RA and forty-five healthy subjects. Serum 25(OH)D levels were measured using Elecsys 25(OH)D reactive kit. Disease activity was assessed according to DAS28, the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The association between serum levels of 25(OH)D and age, gender, disease duration and disease activity parameters were established.

RESULTS: The mean serum 25(OH)D levels were significantly decreased in RA patients compared to healthy controls (p < 0.01) and were associated with higher levels of parathyroid hormone. Vitamin D deficiency (i.e. < 30 ng/ml) was found in 50 patients (90.9 %). Serum levels of vitamin D lower than 20 ng/ml were found in 72 % of patients. We did not find the correlation between serum 25(OH)D levels and disease activity parameters.

CONCLUSIONS: Our findings have demonstrated that serum 25(OH)D levels is highly prevalent in patient with RA. We believe that it will be helpful to investigate the vitamin D levels in order to determine the osteomalacia risk of RA patients (Tab. 2, Ref. 11).