Leukemia is a malignant neoplastic disease of the blood system. Patients with leukemia can be found with abnormal blood counts in their peripheral blood. However, in a few cases, the number of white blood cells is normal or reduced. The most common diseases with a reduced number of white blood cells are hypoproliferative leukemia and acute promyelocytic leukemia patients. Second, the number of red blood cells is generally reduced in patients with leukemia, and all have varying degrees of anemia. However, the morphology of red blood cells is often normal. Third, the number of platelets, most leukemia patients have a serious reduction in the number of platelets, especially in acute leukemia patients, the number of platelets will appear significantly reduced.