Absorption of cobalamin (vitamin B12) administered via jejunostomy

Absorption of cobalamin (Cbl) administered via feeding jejunostomy (J) was compared with that given by mouth (PO) to study the role of transgastric passage in its binding to gastric Intrinsic Factor and subsequent ileal absorption. Modified Schilling tests were performed on 10 patients, each patient serving as his own control. A labeled Cbl capsule was dissolved in 10 cc of water, 7 cc (containing approximately 0.4 microCi 57Co) measured in a syringe and administered PO or via J, followed by 30 cc of water. The remaining solution was used for counting. Starting 1 hour later, following 1 mg of IM cyano-Cbl USP to saturate body storage sites of Cbl, urine was accurately collected for 24 hours and a 4-ml aliquot analyzed for 57Co. Results are expressed as % of tracer excreted in the urine (normal: greater than 7%). The test was repeated in 1 week through the alternate route using the identical protocol. In the eight patients in whom results could be analyzed, absorption was 21.18 +/- 5.83% in J group (range: 5.8-51.9%) and 9.75 +/- 2.62% in PO group (range: 1.9-24.2%). This difference was highly significant p = 0.02) using the paired Student's t-test. Route of the first test (PO or J) made no difference. It is concluded that cobalamin (vitamin B12) administered via jejunostomy is absorbed to a degree significantly greater than that given by mouth.