Vitamin B12 in plasma in patients with continent ileostomy and long observation time.

Plasma cobalamins (vitamin B12) were determined by a microbiological method in 235 patients with continent ileostomies and postoperative observation times of 3-13 years (mean, 6 years). The influence of the reservoir on the vitamin B12 values could not be evaluated in 22 patients (9%)--because of prophylactic treatment in 6%, subnormal B12 values before the operation in 1%, and 'treatment' of various neurological symptoms not caused by vitamin B12 deficiency in 2%. Fourteen (7%) of the remaining 213 patients had developed subnormal plasma levels of vitamin B12 and another 14 patients (7%) had 'borderline' values (130-200 pmol/l). The median time interval between reservoir operation and the development of subnormal values was 7.5 years (range, 3-11 years). A small-bowel resection had been added to the proctocolectomy in 11 out of 14 patients with subnormal values and in 8 out of 14 patients with borderline values. Subnormal or borderline values were seen in 27% of patients with Crohn's disease and in 12% of patients with ulcerative colitis. No patient had anaemia or neurological symptoms caused by B12 deficiency. The study shows that most patients with continent ileostomies do not develop B12 deficiency, and there is therefore no need for general prophylaxis. Since at least 7% developed subnormal values, the plasma levels of vitamin B12 should, however, be followed up regularly in all patients with continent ileostomies.