Objective: Crohn's disease commonly involves the small intestine, which is the site of vitamin B12 and folate absorption. Our aim was to define the prevalence of vitamin B12 and folate deficiency in patients with Crohn's disease and to identify predictive factors associated with such abnormalities.
Methods: Two years prospective study of 180 consecutive Crohn's disease patients. Vitamin B12 and folate deficiency was defined as serum levels below 200 pg/ml and 3 ng/ml, respectively. We analysed prevalence of these deficiencies and possible predictive factors including small intestine resection, disease location, activity and duration of disease. Controls were ulcerative colitis patients (n = 70).
Results: The prevalence of B12 deficiency in Crohn's disease was 15.6% (95%CI 9.7-20%) compared with 2.8% (95%CI 0.8-9.8%) in ulcerative colitis (p = 0.007). With regard to folate deficiency, the prevalence in patients with Crohn's disease was 22.2% (95%CI 16-28%) compared with 4.3% (95%CI 1.4-12%) in ulcerative colitis (p = 0.001); 7.8% of Crohn's disease patients had macrocytic anemia. Ileal resection was found to be a risk factor for B12 deficiency (OR 2.7; 1.2-6.7; p = 0.02), and disease activity a risk factor for folate deficiency (OR 2.4; 1.2-5.1; p = 0.01).
Conclusion: A significant proportion of patients with Crohn's disease suffer from vitamin B12 and/or folate deficiency, suggesting that regular screening should be performed, with closer monitoring in patients with ileal resection or active disease.