Acute folic acid deficiency after bone marrow transplantation.

After bone marrow transplantation (BMT), megaloblastic bone marrow changes are often observed that can only be partially explained by drug effects. Our goal was to find out whether folic acid deficiency represented an additional factor. The serum folic acid concentrations of 41 patients were determined regularly before and after BMT. A 2nd degree polynomial regression analysis revealed a clear and acute drop in folic acid concentrations within 7-9 days after BMT. In 19 patients the level fell below 3.0 ng/ml, the range of folic acid deficiency. The mean folic acid values without oral administration of folic acid after BMT lay significantly below the mean values with substitution (P less than 0.001). If a case of acute graft versus host disease (GvHD) was more severe than grade I, the mean folic acid levels were significantly lower (P less than 0.01). Patients with megaloblastic bone marrow changes after BMT had significantly lower folic acid values than those without such changes (P less than 0.01). The 18 patients with folic acid deficiency had a significantly higher rate of megaloblasts, binucleate erythropoietic precursors, Howell-Jolly bodies, giant myelocytes, and giant metamyelocytes in bone marrow smears than the remaining 23 patients (P less than 0.05). Folic acid deficiency did not slow down the increase in leukocytes, granulocytes, thrombocytes, or reticulocytes after BMT. There were 8.2%-9.7% hypersegmented neutrophils in the blood (normal 5%) after BMT both with and without folic acid deficiency. Folic acid deficiency after BMT was caused by insufficient intake combined with simultaneous decreased intestinal resorption and increased requirements for the regeneration of bone marrow and intestinal mucosa.