Oral Vitamin B_12 without Intrinsic Factor in the Treatment of Pernicious Anemia

Abstract

Twenty-seven patients with pernicious anemia in relapse were treated with oral preparations of vitamin B12 at a dosage of 300 ug/day. Preparations used included hydroxocobalamin, cyanocobalamin, an undifferentiated mixture of cobalamins from microbiologic sources (cobalamin concentrate), and vitamin B12 with Fe and ascorbic acid, with and without liver extract. No intrinsic factor preparations were used. Clinical and hematologic responses were excellent in every case. Serum vitamin B12 levels rose from subnormal to normal levels and were maintained during the duration of the study which lasted up to a year. No significant differences between cobalamin concentrate, cyanocobalamin, and hydroxocobalamin were seen and no adverse effects were noted. In another group of 40 cases, doses of 300 to 900 ug of vitamin B12 were labeled with Co57 and fed to patients in remission. This was followed by a parenteral dose of either hydroxo- or cyanocobalamin. The urinary excretion in 24 hours for the cyanocobalamin group averaged about 1 ug from a 300-ug dose, presumably indicating an absorption of about 3 ug. The urinary excretion of hydroxocobalamin was approximately half that of cyanocobalamin, but other evidence suggests that this is due to reduced excretion rather than reduced absorption. These observations indicate a good clinical response, adequate vitamin B12 blood levels after therapy, and evidence of absorption of apparently adequate amounts of vitamin B12 by the urinary excretion test. It would appear therefore that patients with pernicious anemia can be adequately treated with oral doses of 300 ug of vitamin B12 daily without intrinsic factor.