Thrombocytosis means that the number of platelets exceeds the normal range. Normally, the number of platelets per milliliter of blood is 100,000 to 300,000, and if it exceeds 300,000 per milliliter, it is thrombocytosis. The first is reactive thrombocytosis, which is commonly caused by various infections, as well as trauma and surgery, etc. In this case, the thrombocytosis is generally transient, and the number of platelets will gradually drop to normal after the triggering factors are removed. The second condition is primary thrombocytosis, which is common in various myeloproliferative diseases, such as primary thrombocytosis and true erythrocytosis, where the number of platelets may be abnormally high, often exceeding 1 million platelets per milliliter of blood, and the patient may cause thrombosis or bleeding disorders, often requiring the administration of drugs such as hydroxyurea and interferon.