Vit B12 treatment

To the Editor

I would like to make few comments about the treatment of a 9-month-old breast-fed infant with vitamin B12 deficiency reported by Quentin et al in the recent issue of the journal [1].

His anemia (7.4 g/dl), low blood vitamin B12 level (63 pg/ml), white blood cell count (1,300/μl), elevated serum homocysteine, and methylmalonic acid levels were all compatible with the diagnosis. Since he did not have intrinsic factor deficiency, he responded promptly to 1 mg/d of vit B12 in 4 days by reticulocytosis and elevation of serum B12 level (1,416 pg/ml). But the mother seems to be neglected. If vit B12 were also given to the mother, the infant would not require any more B12 treatment because breast milk would supply the requirement.

With this approach two birds would be killed with one stone.

Actually the infant was given extra vitamin B12. Since its half-life is over 350 days, the daily requirement is about 1 μg. Therefore he was overtreated, I believe.

In addition, in Table 1 “Inherited error of vit B12 metabolism” and “Deficiency of cobalamine metabolism” are mentioned. Could the authors please explain the difference between them?