Serum 25-hydroxyvitamin D concentration in patients with psoriasis and rheumatoid arthritis and its association with disease activity and serum tumor necrosis factor-alpha.

OBJECTIVE To assess vitamin D status in psoriasis and rheumatoid arthritis (RA) patients and to study whether it was associated with disease activity, inflammatory markers, and serum tumor necrosis factor-alpha (TNF-α). METHODS This cross-sectional study was conducted at Riyadh National Hospital, Riyadh, Saudi Arabia between March and September 2012. It included 43 patients with plaque psoriasis, 55 RA patients and 40 healthy controls matched for age. Blood samples were drawn from all participants for assessment of 25-hydroxyvitamin D [25(OH)D], TNF-α, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), parathyroid hormone (PTH), and serum corrected calcium. Disease activity of psoriasis and RA were assessed using Psoriasis Area and Severity Index (PASI) and Disease Activity Score Index of a 28 joint count (DAS28). RESULTS We found a significant difference between psoriatic patients, RA patients, and healthy controls in the mean 25(OH)D (11.74±3.60, 15.45±6.42, and 24.55±11.21 ng/ml; p=0.000). We found that 25(OH)D was not correlated with PASI, DAS28, TNF-α, CRP, or ESR in psoriatic and RA patients. CONCLUSION Serum 25-(OH)D levels are significantly lower in psoriatic and RA patients than in healthy control subjects. Low 25-OHD levels also may provide the rationale for vitamin D supplementation in the treatment of psoriasis and RA. More definitive evidence is also required to demonstrate the clinical benefit of vitamin D supplementation in the treatment of psoriasis and RA.