The relation between ileal resection and vitamin B12 absorption.

Over 15 years, 33 patients, who had had 36 ileal resections that included the terminal ileum, had Schilling tests to measure the absorption of vitamin B12. In 11 patients who had 60 cm or more of ileum removed, only one test was normal, while in 25 patients with less than 60 cm resected, 17 tests were normal. Seven of the patients with over 60 cm of ileum resected had stool-fat estimations and none were normal. Eight of 10 patients who had less than 60 cm of ileum resected had normal stool-fat estimations. Results of the Schilling test, but not of the stool-fat estimations, are proportional to the length of ileal resection, up to 60 cm. Retention of terminal ileum tends to preserve vitamin B12 absorption capacity. Thus, if more than 60 cm of terminal ileum is removed, fat and B12 malabsorption are likely. The Schilling test is an indicator of the degree of terminal ileal dysfunction.