Direct and quantitative vitamin B12 absorption measurement in patients with disorders in the distal part of the bowel. Comparison of stool spot test [SST] with whole body counting in patients with ileal pelvic reservoir, ileostomy or Crohn's disease.

Direct and quantitative vitamin B12 absorption studies were performed in 25 patients with disorders in the distal small intestine using whole body counting as the gold standard. Simultaneously, vitamin B12 absorption was also determined by the more simple stool spot test (SST) which incorporates 51CrCl3 as a nonabsorbable marker. The SST provided a reliable direct and quantitative measure of vitamin B12 absorption in patients with previous ileal resections due to Crohn's disease (CD) (n = 7) as compared with whole body counting. In ulcerative colitis (UC) patients with either an ileal pelvic reservoir (n = 10) or a conventional ileostomy (n = 8), markedly shorter bowel transit times and absence of colon may have hindered sufficient mixture of the tracer and marker isotopes which could explain the false absorption values according to the SST in single patients. Therefore, an intact colon and a near-normal bowel transit time seem to be essential for performance of the SST. Whole body counting showed, as expected, that all CD patients except one had decreased vitamin B12 absorption (median 23%; range 3-39%) (normally > 35%). In UC patients with ileostomy, only one had a markedly decreased vitamin B12 absorption, two borderline normal values, while the rest had normal values (median 54%, range 15-76%). All UC patients with ileal pelvic reservoir had normal vitamin B12 absorption values (median 40.5%, range 36-87%). We conclude that vitamin B12 substitution therapy is probably required in patients with CD with ileal resection.(ABSTRACT TRUNCATED AT 250 WORDS)