Platelet pressure volume is the percentage of platelet volume in the peripheral blood to the total blood volume, which is higher than the normal range. There are two reasons for a high platelet pressure product: an absolute increase in the number of platelets and a relative decrease in plasma volume. Therefore, if the platelet pressure is high, the first thing to clarify is whether it is caused by an absolute increase in the number of platelets or a relative decrease in plasma volume. Generally, the relative decrease of plasma volume often has obvious triggers, such as heavy sweating, violent diarrhea, vomiting and so on. If there are no such factors, the increase in platelet count should be considered, which requires routine blood tests, bone marrow aspiration, and so on, to clarify the cause of the increase in platelet count. The most common is myeloproliferative disorders, such as primary thrombocythemia. For this disease, oral hydroxyurea is required to reduce the platelet count, and if the platelet count is abnormally high, platelet mono-collection can be used to rapidly reduce the platelet count.