Blood is the three components of red blood cells, white blood cells and platelets suspended in a liquid plasma. Therefore, the diseases of the blood system are just three kinds: 1. Red blood cell diseases: various anemias: iron deficiency anemia, megaloblastic anemia, chronic disease anemia, aplastic anemia, pure red blood cell aplastic anemia, maritime anemia (thalassemia). (Red blood cell destruction more) various hemolysis: autoimmune hemolytic anemia, serum sickness, neonatal jaundice, drug hemolysis, infectious hemolysis, abnormal hemoglobinopathy, paroxysmal sleep hemoglobinuria, hemolytic-uremic syndrome, hemolysis due to blood group incompatibility, hereditary spherocytosis. True erythrocytosis. 2, leukocyte diseases: leukopenia, granulocyte deficiency, acute leukemia, chronic granulocytic leukemia, chronic lymphocytic leukemia, leukemia-like reactions, infectious mononucleosis, myelodysplastic syndrome. 3, coagulation disorders: allergic purpura, thrombocytopenia, immune thrombocytopenic purpura, thrombotic thrombocytopenic purpura, hemophilia, vascular hemophilia, disseminated intravascular coagulation, hereditary hemorrhagic capillary dilatation, vascular purpura, fibrinolytic syndrome, hereditary protein C deficiency, hereditary protein S deficiency, hereditary antithrombin III deficiency, abnormal fibrinogenemia, platelet anemia, giant platelet syndrome, primary platelet factor 3 deficiency. Primary thrombocythemia. 4.Lymphoma and others: Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, multiple myeloma, angioimmunoblastoma lymphadenopathy, lymphoma-like granulomatosis, Castleman’s disease, reactive plasma cell disease, macroglobulinemia, heavy chain disease, POEMS syndrome, myelofibrosis, hemochromatosis, amyloidosis, hypersplenism. 5. Unexplained fever, often a manifestation of hematologic disease.