It is very unlikely that platelets above 500 are leukemia. There is only one condition that may be leukemia, and that is chronic granulocytic leukemia. Because chronic granulocytic leukemia is a myeloproliferative disease, the patient will have an abnormally high number of white blood cells in the peripheral blood and sometimes an abnormally high number of platelets, even above 500, but the patient will have a large spleen and the Philadelphia chromosome will be found as a basic feature in the bone marrow cells. In other cases such as acute myeloid leukemia, acute lymphocytic leukemia, and chronic lymphocytic leukemia, the platelet count in the peripheral blood is not likely to be greater than 500 because the normal hematopoietic function is inhibited in these diseases due to the differentiation and proliferation of leukemic cells in the bone marrow, and megakaryocytes are unable to produce normal platelets. 500.