The causes of low platelets generally include decreased platelet generation, increased platelet destruction or consumption, and decreased platelet distribution. 1. Reduced platelet production: it can be seen in tumor patients with radiotherapy injury, aplastic anemia, advanced myelofibrosis, etc., all of which can lead to bone marrow injury, bone marrow hematopoietic stem cells can not be normally differentiated to form megakaryocytes, which can not generate platelets, and thus can cause reduced platelet production. 2. Platelet destruction or increased consumption: it can be seen in severe infection, primary immune thrombocytopenia, disseminated intravascular coagulation. All of them can activate capillary endothelial cells leading to damage, so that a large number of platelet adhesion and aggregation, resulting in increased platelet consumption; also can be seen in cirrhosis caused by increased destruction of platelets in splenic ambassadors, resulting in a decrease in the number of platelets. 3. Platelet distributional reduction: transfusion of large amounts of stock blood, because there are no more surviving platelets in the stock blood, resulting in dilutional thrombocytopenia. The normal value of platelet count is (100~300)×10⁹/L, less than the lower limit of normal value is thrombocytopenia. It is recommended to consult a doctor in time to clarify the cause of the disease and targeted treatment under the guidance of a physician.