Vitamin D deficiency in adult patients with ulcerative colitis: Prevalence and relationship with disease severity, extent, and duration

Background Vitamin D plays a key role in gut immunity and maintenance of the mucosal barrier. Vitamin D deficiency (VDD) worsens ulcerative colitis (UC) and its supplementation ameliorates the disease in mouse models. The prevalence and predictors of VDD in UC are not known. Methods Consecutive patients with UC (n=80) underwent clinical, endoscopic, and histological evaluation to assess the extent, severity using UC disease activity index (UCDAI) score, and duration of illness. An equal number of age and gender-matched healthy adults without any features of inflammatory bowel disease (IBD) living in the same latitude were identified as controls. The serum 25-hydroxy vitamin D-3 level was estimated. The subjects were classified as deficient (<20ng/mL), insufficient (20-32ng/mL), sufficient (32-80ng/mL), and optimal (>80ng/mL) based on vitamin D levels. Chi-square test and Mann-Whitney U test were done to identify factors associated with vitamin D deficiency. Results The patients and controls were similar in age and gender (40 +/- 11.4years, 51% male vs. 40 +/- 12years, 51% male; p=1.000). Median vitamin D levels among patients were lower than the controls (18.1ng/mL [IQR 14] vs. 32.5ng/mL [IQR 36]; p<0.001). Patients were more often VDD (56% vs. 40%) or insufficient (34% vs. 9%) and less often sufficient (9% vs. 40%) or optimal (1% vs. 11%), in contrast to controls (p<0.001). Median vitamin D levels were lower in those with UCDAI >6 (15 vs. 21ng/mL; p=0.01), having pancolitis (13 vs. 21ng/mL, p=0.01), and longer duration of illness >2years (13.8 vs. 20.8; p=0.025). Vitamin D levels showed a negative correlation with frequency of stools (rho=-0.244, p=0.05), disease duration (rho=-0.244, p=0.007) and UCDAI score (r=-0.348, p=0.002). Conclusion VDD is highly prevalent among patients with UC. Patients with longer disease duration, more severe symptoms, and pancolitis are likely to have lower vitamin D levels.