A platelet count of 65 x 10⁹/L is considered low in a 70 year old. Platelet 65 means that the platelet count is 65×10⁹/L, and the normal platelet count is (100~300)×10⁹/L. The causes of low platelet count are: ① decreased generation: common in hematologic diseases, such as aplastic anemia, acute leukemia, advanced myelofibrosis, acute radiation sickness; ② increased consumption: common in certain hematologic diseases, such as primary immune thrombocytopenic purpura, thrombotic thrombocytopenic purpura; ③ distribution abnormalities: splenomegaly or the input of large amounts of stock blood. When there is a 70-year-old man platelets 65 × 10⁹ / L, to the first time to the hospital, further platelet function and number of related examinations, clear cause of the disease under the guidance of physicians active treatment.