Introduction There has been resurgent interest in recent years in the pro-hormone vitamin D beyond its classical role in bone metabolism recognising its plausible effects in immune regulation. The aim of our study was to review practice relating to vitamin D assessment among IBD patients.

Methods We conducted a retrospective review of 300 consecutive patients attending IBD clinics at our hospital. Clinical data including demographics, disease characteristics and therapy were obtained from case note and electronic patient record review. Measurement of serum 25-hydroxyvitamin D (25-OHD) concentration subsequent to IBD diagnosis was noted.

Results Of 300 IBD patients reviewed 141 were female. The median age was 47.5 (range 16–91) and mean disease duration 9.6 years. 137 patients had Crohn's disease, 152 patients ulcerative colitis and 11 patients had IBD-type unclassified (IBDU). 126 (42.0%) patients were current or ex-smokers. Vitamin D status was assessed in 45 (15.0%) patients. In 41 patients (91.1%) measurement was undertaken within the last 2 years. The mean and median serum 25-OHD level was 19.1 and 17.0 ng/ml respectively (range 5–49.9). Nine (20.0%) of these patients had levels <10 ng/ml consistent with deficiency and 17 (37.8%) levels <20 ng/ml. Of the nine patients with vitamin D deficiency (three males; six females), six had Crohn's disease and three had ulcerative colitis. Of the Crohn's patients, three had ileo-colonic, two colonic and one ileal disease. Three had non-stricturing and non-penetrating disease, two stricturing and one penetrating disease. Of the ulcerative colitis patients one had extensive disease, one left-sided disease and one had proctitis. All patients had received steroids during the course of their disease and three patients received azathioprine, four anti-TNF (three infliximab; one adalimumab) and four had previous surgery. Patients with vitamin D deficiency had significant disease requiring immunomodulator, anti-TNF therapy and surgery in this cohort.

Conclusion Vitamin D assessment in IBD patients is suboptimal. Hypovitaminosis D is under-recognised and consequently undertreated. The myriad emerging roles of vitamin D in the pathogenesis of IBD emphasise the importance of recognition and optimisation of vitamin D status to above 30 ng/ml in this patient group.

Competing interests None declared.