Understanding the Many Types of Hemolytic Anemia

Hemolysis is the breakdown of red blood cells. Red blood cells normally live for about 120 days. After that, they die and break down. Red blood cells carry oxygen to all of the body. If red blood cells are breaking down abnormally, there will be fewer of them to carry oxygen. Some diseases and conditions cause red blood cells to break down too soon, causing fatigue and other more serious symptoms.

Types of Hemolytic Anemia

There are many types of hemolytic anemia and the condition can be inherited (your parents passed the gene for the condition on to you) or acquired (you are not born with the condition, but you develop it sometime in your lifetime). The following disorders and conditions are some examples of different types of hemolytic anemias:

• Inherited Hemolytic Anemias: You may have problems with the hemoglobin, cell membrane, or enzymes that maintain your healthy red blood cells. This is usually due to a faulty gene(s) that controls red blood cell production. While moving through the bloodstream, abnormal cells may be fragile and break down.
• Sickle Cell Anemia: A serious inherited disease where the body makes abnormal hemoglobin. This causes the red blood cells to have a crescent (or sickle) shape. Sickle cells usually die after only about 10 to 20 days as the bone marrow can't make new red blood cells fast enough to replace the dying ones. In the U.S., sickle cell anemia mainly affects African Americans.
• Thalassemias: These are inherited blood disorders where the body can't make enough of certain types of hemoglobin, which causes the body to make less healthy red blood cells than normal.
• Hereditary Spherocytosis: When the outer covering of red blood cells (the surface membrane) is defected, red blood cells have an abnormally short lifespan and a sphere, or ball-like, shape. 
• Hereditary Elliptocytosis (Ovalocytosis): Also involving a problem with the cell membrane, red blood cells are abnormally oval in shape, are not as flexible as normal red blood cells, and have a shorter lifespan than healthy cells.
• Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency: When your red blood cells are missing an important enzyme called G6PD, then you have a G6PD deficiency. The lack of enzyme causes your red blood cells to rupture and die when they come into contact with certain substances in the bloodstream. For those who are G6PD deficient, infections, severe stress, certain foods or drugs, can cause the destruction of red blood cells. Some examples of such triggers include antimalarial drugs, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), sulfa drugs, naphthalene (a chemical in some mothballs) or fava beans.
• Pyruvate Kinase Deficiency: When the body is missing an enzyme called pyruvate kinase, red blood cells tend to break down easily.
• Acquired Hemolytic Anemias: When your hemolytic anemia is acquired, your red blood cells may be normal but some disease or other factor causes your body to destroy the red blood cells in the spleen or bloodstream.
• Immune Hemolytic Anemia: In this condition, your immune system destroys healthy red blood cells. The 3 main types of immune hemolytic anemia are:
• Autoimmune Hemolytic Anemia (AIHA): This is the most common hemolytic anemia condition (AIHA accounts for half of all cases of hemolytic anemia). For some unknown reason, AIHA causes your body's own immune system to make antibodies that attack your own healthy red blood cells. AIHA may become serious and come on very quickly. 
• Alloimmune Hemolytic Anemia (AHA): AHA occurs when the immune system attacks transplanted tissue, a blood transfusion, or in some pregnant women, the fetus. Since AHA can happen if the transfused blood is a different blood type than your blood, AHA can also happen during pregnancy when a woman has Rh-negative blood and her baby has Rh-positive blood. Rh factor is a protein in red blood cells and "Rh-negative" and "Rh-positive" refers to whether your blood has Rh factor. 
• Drug-induced Hemolytic Anemia: When a medicine triggers your body's immune system to attack its own red blood cells, it can cause drug-induced hemolytic anemia. Chemicals in medicines (such as penicillin) can attach to red blood cell surfaces and cause the development of antibodies.
• Mechanical Hemolytic Anemias: Physical damage to red blood cell membranes can cause destruction at a faster rate than normal. The damage may be caused by changes in the small blood vessels, a medical device used during open-heart surgery, a faulty artificial heart valve, or high blood pressure during pregnancy (preeclampsia). In addition, strenuous activities can sometimes result in blood cell damage in the limbs (such as running a marathon)
• Paroxysmal Nocturnal Hemoglobinuria (PNH): Your body will destroy abnormal red blood cells (caused by a lack of certain proteins) more quickly than normal with this condition. Individuals with PNH are at an increased risk for blood clots in the veins, and low levels of white blood cells and platelets.
• Hemolytic Disease of the Fetus and Newborn: This hemolytic anemia is seen when the fetus has an incompatible blood type with the pregnant person.

Other Causes of Damage to Red Blood Cells

Certain infections, chemicals, and substances can also damage red blood cells, leading to hemolytic anemia. Some examples include toxic chemicals, malaria, tick-borne diseases or snake venom.

Blood Tests Used to Diagnose Hemolysis

Seeing your healthcare provider is the first step to getting a diagnosis of hemolytic anemia. Your practitioner may evaluate your medical and family history in addition to a physical exam and blood tests. Some blood tests used to diagnose hemolysis are:

• Complete blood count (CBC)
• Red blood cell count (RBC), also called erythrocyte count
• Hemoglobin test (Hgb)
• Hematocrit (HCT)

Newborn screening programs as mandated by each State usually screens (using routine blood tests) for sickle cell anemia and G6PD deficiency in babies. Early diagnosis of these inherited conditions is vital so that children can get proper treatment.