Background: Because vitamin B12 is absorbed exclusively by the terminal ileum, we investigated vitamin B12 deficiency as a potential metabolic complication after urinary intestinal diversion.
Methods: We measured serum levels in patients with Kock pouches (n = 35); Indiana pouches (n = 27); and ileal conduits (n = 25). Serial determinations of serum B12 levels were obtained in 19 patients with kock pouches and 14 patients with Indiana pouches. The dual-isotope Schilling test was performed in 9 patients with Kock pouches and 6 patients with Indiana pouches.
Results: No patient had an abnormally low serum B12 level (< 200 pg/mL). Mean (+/-SD) serum B12 levels in patients with the Kock pouch (506 +/- 202 pg/mL) and the Indiana pouch (536 +/- 249 pg/mL) were lower than that in patients with the ileal conduit (727 +/- 391 pg/mL). The mean serum B12 level was not significantly different between patients with and without preoperative irradiation. Serial determinations showed that serum B12 levels in some patients with continent urinary reservoirs were persistently near the lower normal limit, or became progressively lower. Three of the 9 patients (33%) with Kock pouches and 4 of the 6 patients (67%) with Indiana pouches were B12 malabsorbers, although no patients had megaloblastic anemia or neurologic symptoms.
Conclusions: Some patients with continent urinary reservoirs are at risk for vitamin B12 deficiency due to malabsorption. Routine evaluation of serum B12 levels is recommended for all patients with continent urinary reservoirs, and a Schilling test for those with subnormal serum B12 levels.