Effects of oral crystalline cyanocobalamin 1000 μg/d in the treatment of pernicious anemia: An open-label, prospective study in Ten Patients.

Background: Standard treatment of cobalamin (vitamin B12) deficiency involvesregular (1000 μg/mo) IM cyanocobalamin administration. It has been suggested that high-dose (>2000 μg/d) oral cyanocobalamin may be effective in patients with pernicious anemia.

Objective: The aim of this study was to assess the efficacy and tolerability of oral crystalline cyanocobalamin 1000 μg/d in patients with cobalamin deficiency related to established pernicious anemia.

Methods: This open-label, prospective study was conducted at StrasbourgUniversity Hospital, Strasbourg, France. Patients aged ≥18 years with well-documented cobalamin deficiency related to pernicious anemia were enrolled. Patients received crystalline cyanocobalamin 1000 μg QD PO (capsule) for at least 3 months. Serum cobalamin, folate, iron, and homocysteine concentrations were measured, and a complete blood count was obtained, before (month 0; baseline) and after treatment.

Results: Ten patients (7 women, 3 men; mean [SD] age, 72.1 [15.5] years) entered the study. After 3 months of treatment, serum cobalamin concentration increased in all 9 patients in whom it was measured (mean [SD] increase, 117.4 [30.8] pg/mL; P < 0.001 vs baseline). Serum cobalamin concentrations were normalized (>200 pg/mL) in 6 patients. The serum cobalamin concentration was unavailable in 1 patient because of technical problems. Eight patients had increased hemoglobin concentrations (mean [SD] increase, 2.5 [2.4] g/dL; P < 0.01 vs baseline). All 10 patients had decreased mean erythrocyte corpuscular volumes (mean [SD] decrease, 10.4 [6.2] fL; P < 0.003 vs baseline). Four patients received concomitant blood transfusions or folate and iron supplementation. Three patients experienced clinical improvement in paresthesia, reflex abolition, or combined medullary sclerosis (each, 1 patient).

Conclusion: The results of this small study in patients with cobalamin deficiencyrelated to pernicious anemia suggest that oral crystalline cyanocobalamin 1000 μg/d may be an effective treatment.