Oral cobalamin therapy for the treatment of patients with food-cobalamin malabsorption

Background The standard treatment for cobalamin (vitamin B12) deficiency involves regular intramuscular cobalamin injection. It has been suggested that oral cobalamin therapy may be effective for treating patients who have food-cobalamin malabsorption. Subjects and methods We prospectively studied 10 patients with cobalamin deficiency and well-established food-cobalamin malabsorption who received 3000 μg or 5000 μg of oral crystalline cyanocobalamin once a week for at least 3 months. Complete blood counts and serum cobalamin, homocysteine, and folate levels were determined at baseline and after 3 months of treatment. Patients were reexamined after 6 months. Results After 3 months of treatment, all patients had increased hemoglobin levels (mean increase, 1.9 g/dL; 95% confidence interval: 0.9 to 3.9 g/dL;P<0.01 compared with baseline) and decreased erythrocyte cell volume (mean decrease, 7.8 fL; 95% confidence interval: 0.9 to 16.5 fL;P<0.001). However, 2 patients had only minor, if any, responses. Serum cobamin levels were increased in all 8 patients in whom it was measured. Conclusion Our findings suggest that moderate doses of crystalline cyanocobalamin given orally may be an effective treatment for food-cobalamin malabsorption.