Vitamin B12 levels of 40 healthy children were determined by using the “radioimmunoassay kit” method. They were found to range from 200 to 1250 pg/ml with a mean of 558.8 ± 268 pg/ml.

It was found markedly low (< 100 pg/ml) in two patients only, and these had megaloblastic anemia of vitamin B12 deficiency.

Very high vitamin B12 levels (> 2000 pg/ml) were found in three patients with chronic myeloid leukemia and in a case of preleukemia. A very high level (> 2000 pg/ml) was also found in a case of hemophilia during massive bleeding in the hip joint, but not in the other hemophilic cases.

Keywords: children, hematologic disorders, vitamin B12