Background: It has been suggested that oral cobalamin (vitamin (B12)) therapy may be an effective therapy for treating cobalamin deficiencies related to food-cobalamin malabsorption. However, the duration of this treatment was not determined.
Patients and method: In an open-label, nonplacebo study, we studied 30 patients with established cobalamin deficiency related to food-cobalamin malabsorption, who received between 250 and 1000 microg of oral crystalline cyanocobalamin per day for at least 1 month.
Endpoints: Blood counts, serum cobalamin and homocysteine levels were determined at baseline and during the first month of treatment.
Results: During the first month of treatment, 87% of the patients normalized their serum cobalamin levels; 100% increased their serum cobalamin levels (mean increase, +167 pg/dl; P < 0.001 compared with baseline); 100% had evidence of medullary regeneration; 100% corrected their initial macrocytosis; and 54% corrected their anemia. All patients had increased hemoglobin levels (mean increase, +0.6 g/dl) and reticulocyte counts (mean increase, +35 x 10(6)/l) and decreased erythrocyte cell volume (mean decrease, 3 fl; all P < 0.05).
Conclusion: Our findings suggest that crystalline cyanocobalamin, 250-1000 microg/day, given orally for 1 month, may be an effective treatment for cobalamin deficiencies not related to pernicious anemia.