Vitamin D Levels in Takayasu's Arteritis and a Review of the Literature on Vasculitides

Objective Takayasu's arteritis (TAK) is a chronic, large‐vessel vasculitis. Vitamin D, as a steroidal hormone, has recently been shown to have immunoregulatory and immunosuppressive effects. Low vitamin D levels are demonstrated in various autoimmune disorders. The aim of this study is to investigate vitamin D levels in patients with TAK. A comprehensive review of vitamin D levels in systemic vasculitides (SVs) is also performed. Methods The study included 36 patients with TAK, 28 patients with Behçet's disease (BD) as disease control and 30 sex‐matched healthy controls. Plasma 25‐hydroxy vitamin D (25(OH) vit D) levels were measured with high‐performance liquid chromatography. “Deficiency” was defined as 25(OH) vit D levels below 25 nmol/l and “insufficiency” as below 50 nmol/l. Results Plasma 25(OH) vit D levels were significantly lower in TAK patients (16.93 ± 10.62 nmol/l) than healthy controls (64.63 ± 21.82 nmol/l). Vitamin D level in BD patients (38.8 ± 20.9 nmol/l) is lower than healthy controls but higher than TAK patients. The frequency of vitamin D deficiency was 83.3% in patients with TAK compared to 3.3% in healthy controls. Plasma 25(OH) vit D levels were same between clinically active and inactive patients. In literature review, very few studies were found to investigate vitamin D in SVs. Conclusion We observed a high prevalence of vitamin D deficiency in patients with TAK. As various immune effects of vitamin D on mononuclear cells and arterial endothelium is shown, vitamin D deficiency can be a predisposing factor for immune activation in SV. We therefore suggest monitorization and replacement of vitamin D status in all TAK and other SV patients.