Platelets (PLT), which are produced by bone marrow megakaryocytes and are the smallest cells in the blood, function to promote hemostasis and accelerate coagulation, as well as maintain the integrity of capillary walls. When a blood vessel ruptures, platelets will aggregate at the rupture to form a platelet plug, blocking the rupture and releasing vasoconstrictive substances, ultimately playing a hemostatic role. Therefore, it is obvious that thrombocytopenia will cause bleeding symptoms, including skin and mucous membrane bleeding (skin bruising, petechiae, ecchymosis, nosebleed, gum bleeding, oral mucous membrane bleeding), gastrointestinal bleeding (vomiting blood, blood in stool), urinary bleeding (hematuria), brain hemorrhage, women’s menstruation increased. Thrombocytopenia, once bleeding occurs, especially internal bleeding, is even fatal, so the cause should be actively searched for and treated promptly for the cause. Below we will explain the causes of thrombocytopenia and diagnosis and treatment. Pseudo-thrombocytopenia: For unintentional physical examination found that platelets are significantly reduced, and clinically there are no symptoms of bleeding from skin and mucous membranes and internal organs, pseudo-thrombocytopenia should be considered first. The so-called “pseudo-thrombocytopenia” is due to improper operation, personal constitution EDTA-insensitive or automatic blood cell analyzer inevitably caused by miscalculation, the etiology of the main EDTA-induced agglutination, cold agglutination and platelet – leukocyte rosette knots appear. Thrombocytopenia caused by this situation, can be replaced with “heparin anticoagulant” blood collection tube or can be used to manual platelet count retest. Second, the true thrombocytopenia: mainly including platelet generation, distribution abnormalities and destruction of increased. (1)Thrombocytopenia caused by bone marrow injury: ①Hematological malignancy: such as “leukemia, myelodysplastic syndrome, aplastic anemia”, it is recommended to consult hematology department for bone marrow smear, bone marrow biopsy, gene, chromosome and immunophenotyping, etc., and then support symptomatic treatment, regular chemotherapy and bone marrow transplantation; ②True thrombocytopenia: it mainly includes thrombocytopenia, distribution abnormality and destruction increase. Bone marrow suppression: such as “radiation, chemotherapy, radiotherapy, alcohol overdose, drugs (alkylating agents, chloramphenicol, antimetabolites, thiazide diuretics)”, it is recommended to avoid contact with the above substances, and the platelets may recover gradually. (iii) Viral infections: such as “hepatitis C virus, hepatitis B virus, rubella virus, human immunodeficiency virus (HIV), Helicobacter pylori infection”, etc., it is recommended that targeted antiviral, anti-Helicobacter pylori treatment; (iv) Bone marrow infiltration: such as “metastasis of malignant tumors to the bone marrow,” it is recommended that the treatment of primary tumors, symptomatic supportive care, the general survival is short, and the prognosis is poor. Generally, the survival period is short and the prognosis is poor. (2) Thrombocytopenia caused by congenital genetic factors: for example: Wiskott-Allrich syndrome, effective for splenectomy; autosomal recessive thrombocytopenia. Such patients in puberty can generally be self-relieved; Fanconi anemia, such diseases in addition to bone marrow allogeneic transplantation, there is no other effective treatment. (3) Thrombocytopenia caused by nutritional deficiencies: seen in megaloblastic anemia and iron deficiency anemia combined with thrombocytopenia, such patients are given supplementary hematopoietic raw materials (folic acid, vitamin B12, iron), platelets can gradually rise. 2, platelet destruction increased (1) non-immune factors caused by thrombocytopenia: ① Disseminated intravascular coagulation (DIC): the disease is generally caused by “systemic infection, severe pancreatitis, malignant tumors,” and other diseases caused by coagulation dysfunction, focusing on the active control of the primary disease, to avoid the emergence of DIC, once the risk of fatal Thrombotic thrombocytopenic purpura (TTP): typical TTP in addition to thrombocytopenia, microangiopathic hemolysis, neuropsychiatric abnormalities, renal insufficiency and fever and other manifestations of the disease, the disease has a high mortality rate, once diagnosed, should be actively dealt with, the treatment mainly glucocorticoids, immunosuppressants, anti-platelet aggregation, plasma exchange, etc.; ③ hemolytic uremic syndrome (HUS): the disease is clinically characterized by fever, acute renal function, and the development of the disease. Clinical fever, acute renal failure, microangiopathic hemolysis, thrombocytopenia, but psychiatric symptoms are relatively rare, there is no specific treatment drugs, symptomatic support, can be given to heparin, hemodialysis, peritoneal dialysis treatment. (2) Thrombocytopenia caused by immune factors: ① idiopathic thrombocytopenic purpura (ITP): the disease can be clarified by bone marrow smear and platelet antibody test. Acute ITP is most common in children, sudden thrombocytopenic purpura, the onset of 2 days – 3 weeks before the onset of more than a history of infection (especially viral infections), often 1-2 months with a tendency to spontaneous recovery (self-limiting), the bleeding tendency is mild, no need to intervene; Chronic-type ITP is most common in adults, the natural remission of the more rare, the treatment can be used glucocorticoids (preferred), immunosuppressive agents, splenectomy; ① Secondary to the auto immune diseases: such as systemic lupus erythematosus (SLE), rheumatoid arthritis, Evans syndrome, hyperthyroidism, chronic hepatitis, etc. caused by thrombocytopenia, some patients can thrombocytopenia as the first symptom, months or even years before the corresponding typical symptoms, especially young female patients, should be routinely performed immunity-related antibodies (such as: anti-nuclear antibody, anti-double-stranded DNA, anti-CCP, etc.) antibody screening test, should be routinely performed. ) antibody screening test, it is recommended to clarify the cause of the disease, for the cause of treatment; ③ drug immune thrombocytopenia: such as “aspirin, anti-inflammatory pain, paracetamol and other antipyretic analgesics, penicillin, cephalosporin, sulfa, rifampicin and other antimicrobial drugs, and heparin, carbamazepine, sodium phenytoin, valproate, etc.” Drugs can cause immune platelet destruction, which usually leads to platelet destruction, and usually leads to immune thrombocytopenia, which can lead to platelet destruction, which usually leads to platelet destruction. Platelet destruction, so that thrombocytopenia, usually more acute onset, bleeding is more serious, bleeding symptoms after stopping most of the drugs soon disappear, and hormone therapy often has a faster effect, 7-10 days platelets can rise rapidly. 3.Abnormal distribution of platelets: splenomegaly, hypersplenism (chronic liver disease, cirrhosis, idiopathic myelofibrosis) caused by a large number of platelets aggregated in the splenic pool, so the number of platelets detected in the peripheral blood is significantly reduced.