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Hemolytic Anemia

Hemolytic anemia is a condition in which red blood cells are destroyed and removed from the bloodstream before their normal lifespan is up. The condition can be inherited or acquired.

Inherited Hemolytic Anemias

With inherited hemolytic anemias, one or more of the genes that control red blood cell production are faulty. The defects may involve the hemoglobin, cell membrane, or enzymes that maintain healthy red blood cells.

The abnormal cells may be fragile and break down while moving through the bloodstream. If this happens, an organ called the spleen may remove the cell debris from the bloodstream. Examples:

Sickle Cell Anemia

Sickle cell anemia is a serious, inherited disease. In this disease, the body makes abnormal hemoglobin. This causes the red blood cells to have a sickle, or "C," shape. Sickle cells don't last as long as healthy red blood cells. They usually die after only about 10 to 20 days. The bone marrow can't make new red blood cells fast enough to replace the dying ones.

Thalassemias

Thalassemias are inherited blood disorders in which the body doesn't make enough of certain types of hemoglobin. This causes the body to make fewer healthy red blood cells than normal. Thalassemias most often affect people of Southeast Asian, Indian, Chinese, Filipino, Mediterranean, or African origin or descent.

Hereditary Spherocytosis

In this condition, a defect in the surface membrane (the outer covering) of red blood cells causes them to take on a sphere, or ball-like, shape. These blood cells have a lifespan that's shorter than normal. Hereditary spherocytosis is the most common cause of hemolytic anemia among people of Northern European descent.

Hereditary Elliptocytosis (Ovalocytosis)

This condition also involves a problem with the cell membrane. With this condition, the red blood cells are elliptic (oval) in shape. They aren't as flexible as normal red blood cells, and they have a shorter lifespan.

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency

In G6PD deficiency, the red blood cells are missing an important enzyme called G6PD. G6PD is part of the normal chemistry inside red blood cells. In G6PD deficiency, if red blood cells come into contact with certain substances in the bloodstream, the missing enzyme causes the cells to rupture and die. A number of factors can trigger the breakdown of the red blood cells. Examples include taking sulfa or antimalarial medicines; being exposed to naphthalene, a substance found in some moth balls; eating fava beans; or having an infection. G6PD deficiency mostly affects males of African or Mediterranean descent. It affects about 1 in 10 African American males.

Pyruvate Kinase Deficiency

With this condition, your body is missing an enzyme called pyruvate kinase. Not having enough of this enzyme causes red blood cells to break down easily. This disorder is more common among the Amish than other groups.

Acquired Hemolytic Anemias

With acquired hemolytic anemias, your red blood cells may be normal. However, some other disease or factor causes the body to destroy red blood cells and remove them from the bloodstream. The destruction of the red blood cells occurs in the bloodstream or, more commonly, in the spleen.

Immune Hemolytic Anemia

In immune hemolytic anemia, your immune system destroys your red blood cells. The three main types of immune hemolytic anemia are: autoimmune, alloimmune, and drug-induced.

Autoimmune hemolytic anemia (AIHA). In this condition, your immune system makes antibodies (proteins) that attack your red blood cells. Why this happens isn't known. AIHA accounts for half of all cases of hemolytic anemia. AIHA may come on very quickly and become serious. It's most common in people older than 40.

Having certain diseases or infections can raise your risk for AIHA. Examples include:

  • Autoimmune diseases, such as lupus
  • Chronic lymphocytic leukemia
  • Non-Hodgkin's lymphoma and other blood cancers
  • Epstein-Barr virus
  • Cytomegalovirus
  • Mycoplasma pneumonia
  • Hepatitis
  • HIV

In some types of AIHA, the antibodies made by the body are called warm antibodies. This means they're active (that is, they destroy red blood cells) at warm temperatures, such as body temperature.

In other types of AIHA, the body makes cold-reactive antibodies, which become active in colder temperatures. Cold-reactive antibodies can become active when parts of the body, such as the hands or feet, are exposed to temperatures lower than 32 to 50 degrees Fahrenheit (0 to 10 degrees Celsius).

Warm antibody AIHA is more common than cold-reactive antibody AIHA.

Alloimmune hemolytic anemia. This type of hemolytic anemia occurs if your body makes antibodies against red blood cells that you get from a blood transfusion. This can happen if the transfused blood is a different blood type than your blood. This type of hemolytic anemia also can occur during pregnancy if there's a difference in blood type between the mother and the fetus.

Drug-induced hemolytic anemia. Certain medicines can cause a reaction that develops into hemolytic anemia. Some medicines, such as penicillin, bind to red blood cell surfaces and can cause antibodies to develop. Other medicines cause hemolytic anemia in other ways. Examples of such medicines include acetaminophen; quinine and antimalarial medicines; anti-inflammatory medicines; and levodopa.

Mechanical Hemolytic Anemias

Physical damage to red blood cell membranes can cause them to break down faster than normal. Damage may be due to:

  • Changes in the small blood vessels.
  • An artificial heart valve or other device used in blood vessels.
  • A heart-lung bypass machine, which may be used during open-heart surgery.
  • Preeclampsia or eclampsia. Preeclampsia is high blood pressure during pregnancy. Eclampsia, which follows preeclampsia, is a serious condition that causes seizures in pregnant women.

Blood cell damage also may occur in the limbs while participating in marathons or other strenuous activities.

Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a disorder in which the red blood cells are abnormal due to a lack of certain proteins. The body destroys these cells more quickly than normal. People who have PNH are at increased risk for blood clots in the veins and low levels of white blood cells and platelets.

Other Causes of Damage to Red Blood Cells

Certain infections and substances also can damage red blood cells and lead to hemolytic anemia. Examples include malaria and blackwater fever, tick-borne diseases, snake venom, and toxic chemicals.

 

Source

National Heart, Lung, and Blood Institute, USA.