The number of platelets in the peripheral blood of a normal person is 100,000-300,000/mL, and less than 100,000/mL is thrombocytopenia. There are many causes of thrombocytopenia, the common ones are: i. Secondary thrombocytopenia, such as viral infections, certain drugs, anti-inflammatory and painkillers, can cause thrombocytopenia. Second, the case of hypersplenism, due to the enlargement of the spleen, some platelets are retained in the spleen, resulting in a decrease in the number of platelets in the peripheral blood. Third, hematological system diseases, such as aplastic anemia, may also result in thrombocytopenia due to hematopoietic failure and decreased ability of hematopoietic stem cells to produce platelets. Fourth, hematological system malignancies, such as leukemia patients, due to the proliferation of leukemia cells in the bone marrow, the normal hematopoietic function is destroyed and peripheral blood platelet reduction occurs. Five, immune thrombocytopenia, which is an autoimmune disease, due to the production of autoantibodies, resulting in excessive destruction of platelets in the peripheral blood, causing a decrease in the number of platelets.