Background: Treatment with vitamin B12 has virtually no side effects; however, life-long treatment is inconvenient for the patient and constitutes a cost for society.
Objective: To investigate whether vitamin B12 injection treatment reflects the actual need for treatment or whether some patients are treated unnecessarily with vitamin B12 injections.
Material and methods: A prospective intervention study was conducted among nine general practitioners in Western Sealand County, Denmark. Forty-four patients older than 18 years who had received injection therapy with vitamin B12 for a median of eight years (range 1-26 years) were included. After discontinuation of vitamin B12 injections, blood samples were analysed monthly for hemoglobin, cobalamin, holotranscobalamin, homocysteine and methylmalonic acid. The capacity to absorb vitamin B12 was examined after a median of 13 months (range 5-32 months) by measurement of holotranscobalamin or cyanocobalamin on transcobalamin before and after 1 and 2 days intake of 3 × 9 μg of vitamin B12. Patients unable to absorb the vitamin continued treatment with vitamin B12 injection. The remaining patients participated in a follow-up study receiving 9 μg oral vitamin B12 daily or no vitamin B12 substitution.
Results: Of the 44 patients studied, 35 patients were able to absorb vitamin B12. None of the patients included in the follow-up study showed biochemical signs of vitamin B12 deficiency by the end of the study.
Conclusion: Our results suggest that the capacity for absorbing vitamin B12 should be examined prior to the choice of treatment.
Trial registration: ClinicalTrials.gov NCT00326833.