Diagnosis of hemolytic anemia refers to anemia caused by the destruction of red blood cells. The following tests are usually required for the diagnosis of hemolytic anemia: 1. Auxiliary tests for red blood cell destruction: including the presence of decreased hemoglobin in the blood, red blood cell fragments visible in peripheral blood smears, elevated total bilirubin in the blood biochemical examination, in which indirect bilirubin, i.e. free bilirubin, is predominant, and iron-containing hemoglobin in the urine examination The results of these auxiliary examinations suggest the occurrence of erythrocyte destruction; 2. Auxiliary examinations of bone marrow compensatory hyperplasia: including active bone marrow hyperplasia, increased reticulocyte count, and nucleated red blood cells can be seen in peripheral blood smears; 3. Auxiliary examinations of etiology: such as autoimmune hemolytic anemia and warm antibody-based hemolytic anemia, patients will have a positive direct anti-human globulin test, while cold antibody-based hemolytic anemia will show a positive condensation set test. In patients with hemolytic anemia due to paroxysmal hemoglobinuria, a positive acid hemolysis test or an increased percentage of CD55 and CD59 negative cells on flow cytology may be seen.