Effect of Myleran and 6-Mercaptopurine (6-MP) on the Serum Level of Vitamin B₁₂ in Chronic Myelocytic Leukemia

Serum vitamin B₁₂ determinations and the total leukocyte counts were made at regular intervals in chronic myelocytic leukemia patients before, during and after therapy with 6-MP or Myleran. The results indicate that a reduction in total leukocytes following therapy is followed by a gradual lowering of serum vitamin B₁₂. The levels of serum vitamin B₁₂ at the completion of therapy may be related to the duration of remission.