A high platelet count means that the number of platelets in the peripheral blood is outside the normal range. In clinical practice, normal human peripheral blood contains 100,000-300,000 platelets per milliliter of blood, and more than 300,000 is thrombocytosis. There are two types of clinical causes of thrombocytosis: the first type of cause is thrombocytosis caused by external factors, also known as reactive thrombocytosis, long-term causes include infection, trauma surgery, trauma and so on. Especially some relatively large surgeries, such as open-heart surgery, open-heart surgery and so on. Due to the stimulation of external factors, the platelet count may be increased, and when the external factors are removed, the platelet count will gradually return to normal. The second type of cause is primary thrombocytosis, which is common in various myeloproliferative diseases, such as primary thrombocytosis and true erythrocytosis, which can also result in an abnormally high platelet count.