The vitamin B12 absorption test, CobaSorb, identifies patients not requiring vitamin B12 injection therapy

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 x 9 mu g 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 mu g 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.