High white blood cell count is not necessarily leukemia. If high white blood cell count is found in routine blood test, and at the same time, it is also necessary to see whether there is a decrease in hemoglobin concentration and platelet count, and at the same time, if the patient has symptoms such as enlarged liver, spleen and lymph nodes, as well as pressure pain in the sternum, the possibility of leukemia will be considered, and the confirmation of the diagnosis will require further tests such as peripheral blood cell classification, bone marrow aspiration, and so on. Besides leukemia, the most common diseases that can cause high white blood cell count in peripheral blood are infectious diseases, such as certain serious bacterial infections, which can lead to the release of leukocytes from the bone marrow into the peripheral blood, thus causing an increase in white blood cell count.