Oral B12 in Crohnʼs Disease: Is B12 by injection obsolete?

Abstract

It has been known for several years that there is an alternate pathway for vitamin B12 absorption that requires neither Intrinsic Factor nor the terminal ileum. It was established many years ago that resection of more than 60 cm of ileum almost always results in B12 malabsorption. To replace monthly B12 injections with daily high dose oral B12 in patients with Crohn's disease. Patients with more than 60 cm of ileal resection and/or disease were assumed to have B12 malabsorption. For patients with less than 60 cm ileal resection and/or disease, a Schilling test was performed. A trough serum B12 was obtained for each patient just prior to the due date of the next B12 injection. Oral B12 therapy was then started, with one tablet of 1200 mcg, once daily. Serum B12 levels were measured at 3 and 6 months. Six patients declined to switch to oral therapy; their reasons were recorded. Of 30 patients, all but one attained or maintained normal serum B12 levels. In many patients, the levels increased from baseline values, including 4 patients with short bowel syndrome. However, compliance with follow-up testing was fair, meaning that some patients had to be contacted and reminded to get their levels checked. For the one patient whose 3-month level was below normal, his dose was increased to 2 tablets daily, with a small improvement. High-dose oral B12 tablets should be the first choice for Crohn's patients with ileal resection and/or disease sufficient to produce vitamin B12 malabsorption. B12 injections should be reserved for those people who fail oral therapy, or who are reimbursed for injection therapy and cannot afford the cost of oral therapy.