Platelet index 85×10⁹/L is a mildly low platelet, but from the index most patients are not very serious, but considering the disease factors that cause thrombocytopenia, such as leukemia, it is more serious. The normal value of platelet is (100~300)×10⁹/L, platelet index 85×10⁹/L indicates that the platelet is low, and the common causes are caused by hematologic diseases, infectious diseases, and drug effects. 1. Blood system diseases: such as aplastic anemia, acute leukemia, etc., more serious, need to be timely targeted treatment. For example, acute myeloid leukemia should be treated with drugs such as cytarabine. 2. Infectious diseases: some viral infections can cause a slight decrease in platelets, such as viral pneumonia. 3. Drugs: there are many drugs that cause thrombocytopenia, such as antipyretic and analgesic aspirin, ibuprofen, antibiotics such as cephalosporin, sulfonamides such as lorazepam, etc., and sedative-hypnotic drugs such as flunitroprusside, methylpropionate, etc. If the above drugs cause thrombocytopenia, it will be treated with cytarabine and other drugs. If the above drugs cause low platelets, it is recommended to stop using them under the guidance of a doctor. The above test results alone can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results in order to make an accurate judgment, it is recommended that under the guidance of the doctor to clarify the cause of the disease, timely treatment.