3. Excessive red blood cell destruction (hemolysis) anemia
A red blood cell usually lives for 110-120 days, after which it breaks down and is removed by the spleen. Some illnesses and conditions cause red blood cells to die too early. When this happens the bone marrow has to make more red blood cells than normal. If the bone marrow cannot keep up with the needed red cell production caused by their early deaths, the red blood cell count will start to fall, leading to hemolysis (anemia caused by excessive red blood cell destruction)