Blood tests can check a very wide range of items, including the functional status of various organs and systemic conditions, such as the presence of infections, blood system diseases, allergies and so on. 1. General blood test. It can detect the presence of anemia and its type, infections, blood diseases, allergies, parasites, etc. 2. Bone marrow cytology. It can assist in the diagnosis of hematopoietic system diseases, such as various types of leukemia. 3. Blood group identification and cross-matching test. It plays an important role in the clinical practice of blood transfusion, organ transplantation and hematopoietic stem cell transplantation. 4. Platelet test, coagulation factor test, anticoagulation system test, fibrinolytic activity test. It mainly detects the status of anticoagulant and anticoagulant system. 5. The status of various organs. Such as cardiac enzymes can detect the presence of myocardial injury, transaminases can evaluate liver function. 6. Specificity factors. Cancer-specific markers can assist in the diagnosis of cancer, determine the prognosis, etc. For example, carcinoembryonic antigen and alpha-fetoprotein can find out whether the examinee suffers from colon cancer or liver cancer. When the blood test results are abnormal, active diagnosis and treatment are needed.