Changes in serum erythropoietin and the reticulocyte count during chemotherapy for leukemias

We serially determined serum erythropoietin (Epo) and the reticulocyte count in patients with various types of leukemia during chemotherapy. Serum Epo increased soon after the initiation of chemotherapy and decreased after the termination of therapy irrespective of the types of leukemia or treatment regimen. However, it did not stay at low level but fluctuated. The reticulocyte count, on the other hand, showed a transient rise while serum Epo level descended. The value of serum Epo when increased was higher than the value expected from hemoglobin concentration; this finding was similar to that in aplastic anemia. These results suggest that myelosuppression is a major factor for the increase in serum Epo level during leukemia chemotherapy.