Vitamin B12 absorption after allogeneic bone marrow transplantation.

The B12 absorption test (Schilling test) with intrinsic factor was used to examine ileal B12 absorption in 26 patients after allogeneic transplantation. The test was well tolerated and showed a profound fall in B12 absorption, which was maximal at two weeks after transplantation and recovered by eight weeks. The predominant influence on absorption at this stage was probably the conditioning schedule, and the presence of acute graft versus host disease (GVHD) was not associated with a further impairment of absorption. Six patients with chronic GVHD were studied. When compared with nine patients without GVHD there was a significant (p less than 0.005) reduction of B12 absorption. These findings suggest that the B12 absorption test may be a useful non-invasive method of studying bowel function after bone marrow transplantation.