Vitamin D Levels in Patients With Small and Medium Vessel Vasculitis.

OBJECTIVES: To determine the prevalence of vitamin D deficiency in patients with small and medium vessel systemic vasculitis. METHODS: In this cross-sectional study, 25-hydroxy (OH) vitamin D3 levels were measured in adult patients with systemic small and medium vessel vasculitis including antineutrophil cytoplasmic antibody-associated vasculitis (AAV), cryoglobulinaemic vasculitis (CryV), IgA vasculitis (IgAV) and polyarteritis nodosa (PAN), and age- and sex-matched healthy subjects (HS) and patients with rheumatoid arthritis (RA) as control groups. 25OH vitamin D3 levels<30ng/ml and <20ng/ml were regarded as insufficiency and deficiency, respectively. RESULTS: Fifty-seven patients (42 AAV, 2 CryV, 8 IgA vasculitis, 5 PAN) with systemic vasculitis, 101 HS, and 111 RA patients were included. The mean 25OH vitamin D3 level was 21.8±14.2ng/mL in patients with vasculitis, 42.7±27.6ng/mL in HS (p<.001) and 20.1±18.47ng/mL in patients with RA (p=.54). Vitamin D insufficiency and deficiency were significantly higher in patients with systemic vasculitis compared to HS (75.4% vs 33.7%, p<.001; %50 vs 21.8%, p<.001, respectively). Vitamin D status was not different in patients with systemic vasculitis compared to RA. There was a negative correlation between vitamin D status and CRP levels (=-.364, p=.007). The multivariate logistic regression analysis showed that renal involvement was significantly associated with vitamin D deficiency/insufficiency in patients with vasculitis (OR 22.5 [95% CI 1.6-128.9]. CONCLUSION: Vitamin D deficiency and insufficiency are more frequent in patients with systemic small and medium vessel vasculitis and RA than HS. Renal involvement is one of the factors associated with vitamin D deficiency/insufficiency in patients with vasculitis.