Hemolytic anemia is a type of anemia. The term "anemia" usually refers to a condition in which the blood has a lower than normal number of red blood cells. Anemia also can occur if your red blood cells don't contain enough hemoglobin. Hemoglobin is an iron-rich protein that carries oxygen from the lungs to the rest of the body.

Anemia has three main causes: blood loss, lack of red blood cell production, or high rates of red blood cell destruction. Hemolytic anemia is caused by high rates of red blood cell destruction. Many diseases, conditions, and factors can cause the body to destroy its red blood cells. These causes can be inherited or acquired. "Inherited" means your parents passed the gene for the condition on to you. "Acquired" means you aren't born with the condition, but you develop it. Sometimes the cause of hemolytic anemia isn't known.