Clinical factors are associated with vitamin D levels in IBD patients: A retrospective analysis

OBJECTIVE There is growing evidence that vitamin D deficiency plays a role in the development and the course of inflammatory bowel disease (IBD). However, the correlation between vitamin D deficiency and clinical parameters in IBD is still not completely understood. METHODS A retrospective study of IBD patients was performed. Vitamin D values were analyzed, regardless of vitamin D substitution administration, and correlated with clinical parameters such as medical therapy, anatomical situation, location of the disease and disease activity. Level of 25‐hydroxyvitamin D [25(OH)D] <50 nmoL/L was regarded as vitamin D deficiency and <75 nmoL/L as insufficiency. RESULTS In total, 208 IBD patients were analyzed, including 123 with Crohn's disease (CD) and 85 with ulcerative colitis (UC). Therapy with azathioprine did not affect the vitamin D values of either disease entity. But CD patients benefited from therapy with tumor necrosis factor‐α inhibitor and exhibited significantly higher vitamin D levels than those without. Furthermore, significantly lower vitamin D levels were found if CD was located in the small bowel or if the small bowel had been resected. Moreover, significantly lower levels of vitamin D were detectable for high disease activity (reflected by high simple clinical colitis activity index values) in patients with UC. CONCLUSIONS Vitamin D deficiency is common in patients with IBD. However, certain clinical situations lead to significantly lower vitamin D levels and may therefore require close monitoring for vitamin D deficiency.