Hypercobalaminemia in myeloid and lymphoid malignancies

Cobalamin, or vitamin B12, is used as a cofactor in a wide range of enzymatic reactions, including the regulation of homocysteine levels and DNA synthesis. Under physiologic circumstances, approximately 80% of the serum cobalamin is bound to haptocorrin, whilst 20% is bound to transcobalamin. The latter protein facilitates the cellular uptake of cobalamin where it can perform its function.