Hemolytic anemia is not leukemia. Normal red blood cell life span is 120 days. Hemolytic anemia is anemia that occurs when the destruction of red blood cells accelerates and shortens their life span, exceeding the hematopoietic capacity of the bone marrow. The normal bone marrow has 6-8 times the hematopoietic capacity of red blood cells. If the rate of red blood cell destruction is within the compensatory range of the bone marrow, although hemolysis is present, anemia may not occur, which is called hemolytic disease or hemolytic state. Hemolytic anemia occurs when the life span of red blood cells is particularly shortened, less than 15 days or even less, and the bone marrow cannot compensate. There are many causes of hemolytic anemia, both hereditary and acquired. In adults, most of them are acquired, such as autoimmune hemolytic anemia and paroxysmal sleep hemoglobinuria. Clinical hemolytic anemia is divided into two major categories, chronic hemolysis and acute hemolysis, depending on the severity and speed of occurrence. Chronic hemolysis has a longer duration and is generally milder, and can manifest jaundice, anemia, splenomegaly, and, in the case of long-term hemolysis, patients can develop secondary stones. Acute hemolysis patients can have chills, high fever, back pain, tea-colored urine, soy sauce-colored urine, and even shock.