A platelet count of 404 x 10^9/L is a condition of high platelets. When the platelet count exceeds 450 x 10^9/L, it can only assist in identifying as thrombocythemia. It is recommended that the patient can improve the relevant examination to clarify the cause of the disease. The normal value of platelets is (100~300)×10^9/L, and a platelet count of 404×10^9/L belongs to the condition of elevated platelets, but does not meet the criteria for thrombocytosis. 1. Elevated platelet count commonly may be due to anemia, blood loss, infection, malignancy, trauma and other causes of temporary platelet count elevation. After controlling the primary disease, the platelet count will gradually return to normal, e.g. levofloxacin anti-infection treatment. 2. Elevated platelet count can also be seen in primary thrombocythemia, true erythrocytosis, chronic granulocytic leukemia, etc., which need to be treated in time, such as primary thrombocythemia to be treated with oral hydroxyurea, aspirin and other drugs. Patients do not need to worry too much, it is recommended to improve the blood smear, C-reactive protein, erythrocyte sedimentation rate, bone marrow smear, coagulation function test and other tests to help clarify the cause of the disease. It is recommended that patients can go to the hospital regularly to review and test the platelet count in the blood. Specific diagnosis and treatment are carried out under the guidance of physicians.