Leukemia cannot be detected by finger blood, first understand what is leukemia, leukemia is due to the abnormal cloning and proliferation of hematopoietic stem cells in the bone marrow caused by the disease, its essence is the bone marrow has bad cells crazy growth, so the gold standard for the diagnosis of leukemia is bone marrow aspiration, indeed see the bone marrow has crazy growth of abnormal cells, and the number of these cells is greater than 20% to confirm the diagnosis. Peripheral blood alone can only be suspected, not confirmed as leukemia, so why is peripheral blood an aid in the diagnosis of leukemia? Because the abnormal cells in the bone marrow grow like crazy and the normal cells are reduced. The crazy cells that enter the peripheral blood can be seen to have a high number of white blood cells, but they are actually non-functional, and the red blood cells, platelets and functional white blood cells that enter the peripheral blood are reduced.