Leukemia is a clonal, malignant proliferative disease of the hematopoietic system. Routine screening is based on routine blood tests of the underlying peripheral blood. Routine blood tests usually show abnormalities in the number or quality of blood cells, mainly as follows: 1. manifesting as increased white blood cells, commonly seen in acute leukemia, chronic granulocytic leukemia, chronic lymphocytic leukemia and chronic monocytic leukemia; 2. manifesting as decreased white blood cells, often called hypoproliferative leukemia; 3. manifesting as decreased red blood cells 4, manifested as decreased hemoglobin; 5, manifested as thrombocytopenia.