Vitamin B12 malabsorption in patients with limited ileal resection

Patients with Crohn's disease who have terminal ileal resections are at risk for vitamin B12 malabsorption. Our aim was to determine whether the length of terminal ileum resected correlated with an abnormal Schilling test result.

Patients with a history of ileal resection had the length of small bowel removed determined by review of their pathology report. Patients who had a Schilling test within 3 mo of surgery or who had a documented normal terminal ileum at the time of the Schilling test were included in the study.

Fifty-six patients were included in the study. Patients who had <20 cm of terminal ileum resected (n = 14) did not develop abnormal Schilling test results; 52% of the remainder (n = 42) had abnormal Schilling test results and there was no clear correlation between resection length and abnormal Schilling test result.

Patients with Crohn's disease and terminal ileal resections <20 cm are not at risk of developing vitamin B12 deficiency. For patients with resections of 20-60 cm, options include doing a Schilling test and treating those with abnormal results, empirically treating patients on the presumption that they are at high risk of developing deficiency, or monitoring for biochemical evidence of deficiency. Further studies are needed to determine whether oral supplementation is effective in these patients.