Hemolytic Anemia [1]

 

What Is It?

Anemia is an abnormally low level of red blood cells. Hemolytic anemia is the general name for any type of anemia that occurs because red blood cells are being destroyed too quickly.

Red blood cells are disc-shaped cells that contain hemoglobin and carry oxygen in the blood. Under normal circumstances, red blood cells are produced in the bone marrow and released into the bloodstream, where they circulate for 110 to 120 days. At the end of this period, the old red cells normally are removed from the blood by the spleen and liver.

In people with hemolytic anemia, red blood cells have an abnormally short life span. There are two major causes of this decrease in life span — either there is a defect in the red blood cell itself, or the red blood cells are normal but are destroyed by an external process.

Many different medical problems can cause hemolytic anemia, including:

  • Inherited abnormalities in the protective outer coating of red cells, the cell membrane — In these genetic (inherited) illnesses, defects in proteins in the cell membrane cause changes in the shape of red cells. Instead of being disc-shaped, the abnormal red cells form spheres, ellipses or tiny cups. These cells are more rigid than normal, and they become targets for the spleen, which identifies them as abnormal and removes them from circulation. These inherited illnesses include hereditary spherocytosis, hereditary elliptocytosis, hereditary stomatocytosis and hereditary poikilocytosis.


  • Inherited enzyme deficiencies inside red blood cells — Enzymes are proteins that drive the chemical reactions inside cells. When enzyme levels are abnormally low inside red blood cells, the cells become very fragile and prone to being destroyed too quickly. The two most common inherited enzyme deficiencies that cause hemolytic anemia are pyruvate kinase deficiency (low levels of the enzyme pyruvate kinase) and G6PD deficiency (low levels of glucose-6-phosphate dehydrogenase).


  • Hemoglobin disorders — These illnesses are characterized by an inherited abnormality affecting the hemoglobin inside red blood cells. They include sickle cell anemia, other less common forms of hemoglobinopathy (an inherited illness in which hemoglobin has an abnormal structure), and the thalassemias (inherited illnesses that affect the cell’s ability to produce hemoglobin.)


  • Physical damage to red blood cells — Hemolytic anemia can occur when red blood cells are damaged in any of the following situations: as they pass through machines that oxygenate blood outside the body during heart-lung surgery; as they flow near prostheses, especially artificial heart valves; or if they are exposed to extreme heat, as in a patient with severe, extensive burns.


  • An autoimmune response — In this case, hemolytic anemia occurs because the body’s immune system mistakenly destroys its own red blood cells. Autoimmune hemolytic anemia is more common in people with other autoimmune conditions, such as systemic lupus erythematosus (SLE or lupus), but it also can occur because of certain types of infections or medications (such as penicillin); in some cases, it has no clear cause.


  • Hypersplenism — Here, an overactive, enlarged spleen traps circulating red blood cells and destroys them.


  • Complication of certain infections — Some viral and bacterial infections cause red blood cells to be destroyed faster than normal.

Symptoms

Symptoms vary widely. In people with milder forms of hemolytic anemia, such as thalassemia minor, red blood cell levels may not drop low enough to cause symptoms of anemia. In these patients, the condition may be discovered only when routine blood tests show mild anemia or abnormalities in the shape of red cells.

In other people, obvious symptoms of anemia can develop. These include:

  • Pale skin
  • Fatigue
  • Weakness
  • Dizziness
  • Lightheadedness
  • Rapid pulse
  • Heart murmur
  • Breathlessness
  • Jaundice (yellowing of the skin and eyes)
  • Dark tea-colored urine

Diagnosis

Your doctor will review your medical history and ask you to describe your symptoms. Other questions may include:

  • Do you have close relatives who have sickle cell anemia, thalassemia, pyruvate kinase deficiency, glucose-6-phosphate deficiency or another form of inherited anemia?
  • What medications do you take? (Include all medications you have taken in the past couple of months.)
  • Have you recently had a severe infection, especially mononucleosis or pneumonia?
  • Do you have an artificial heart valve, a synthetic graft in your blood vessels, or other implants or prostheses?
  • Do you have any other medical problems — especially autoimmune diseases such as lupus or rheumatoid arthritis?

During your physical examination, your doctor will look for signs of anemia (pale skin and fingernails, rapid pulse, heart murmur) and an enlarged spleen and liver, which can occur with anemia. This exam will be followed by blood tests to measure levels of red blood cells, look at the size and shape of red cells, measure the hemoglobin level, and determine the number of reticulocytes. Reticulocytes are immature red blood cells that leave the bone marrow too early because the marrow is pouring out new red cells rapidly to try to make up for the anemia. Your doctor also may order tests to check for blood in your stool (to check for anemia as a result of blood loss), as well as blood tests to check for anemia resulting from a lack of iron or certain vitamins in your diet.

Depending on the suspected cause of your hemolytic anemia, other tests may include:

  • The Coombs’ test — This blood test checks for hemolytic anemia caused by an abnormal immune reaction.
  • G6PD Levels — This blood test looks for a deficiency in this enzyme.
  • Hemoglobin electrophoresis — This blood test checks for abnormal hemoglobin.

Expected Duration

How long hemolytic anemia lasts depends on its cause.

In general, when hemolytic anemia is caused by a medication or infection, it is a temporary problem that goes away when the drug is discontinued or the infection is treated.

When hemolytic anemia is caused by an inherited illness, it is a lifelong condition. However, the impact of this condition on a person’s quality of life and life span can vary greatly, depending on the specific type of inherited disorder and its severity. Some patients have only laboratory evidence of the disorder and no symptoms, whereas others have severe, persistent symptoms.

Prevention

Hemolytic anemia resulting from medication can be prevented by avoiding the drug that is causing the problem. There is no way to prevent the inherited forms of hemolytic anemia, although gene therapy may be possible in the future. If an inherited anemia runs in your family, you and your spouse may wish to speak to a genetic counselor about genetic testing to assess your chances of passing an inherited anemia to your children.

Treatment

Treatment for hemolytic anemia depends on its cause and severity.

  • Inherited abnormalities in the membranes of red cells — If hemoglobin levels are adequate (usually more than 10 grams per deciliter), then treatment may not be necessary. If hemoglobin levels drop very low, a blood transfusion may be needed. In rare cases, the spleen is removed to decrease the destruction of circulating red blood cells.


  • Inherited enzyme deficiencies inside red cells — For severe symptoms of anemia, blood transfusions are necessary.


  • Hemoglobin disorders — In some people with inherited hemoglobin disorders, the illness is mild or does not cause any symptoms (as in thalassemia minor), so treatment is not necessary. People with more severe forms of thalassemia, such as beta thalassemia major, require repeated blood transfusions, and some may be candidates for bone-marrow transplantation. Depending on the severity of symptoms, sickle cell anemia may be treated with folic acid supplements, blood transfusions, antibiotics to prevent infections, and a drug called hydroxyurea (Hydrea).


  • Physical damage to red blood cells — Depending on the severity of symptoms, this may be treated with folic acid and iron supplements and sometimes blood transfusions.


  • An autoimmune response — The treatment of autoimmune hemolytic anemia depends on the cause and the severity. If a trigger (such as a drug or an infection) for the autoimmune response is identified, treatment for hemolysis may not be necessary. Stopping the drug or recovering from the infection may be sufficient. For more severe cases, treatment may include corticosteroid medication such as prednisone, intravenous immune globulin infusions, immunosuppressive drugs such as azathioprine (Imuran) and cyclophosphamide (Cytoxan, Neosar), and removal of the spleen.


  • Hypersplenism — For severe symptoms, the spleen is removed.

When To Call A Professional

Call your doctor promptly if you develop symptoms of anemia or if you notice a yellowish tint in your skin or in the whites of your eyes.

If an inherited form of anemia runs in your family, you may wish to speak to your doctor about genetic testing and genetic counseling before you start a family of your own.

Prognosis

The prognosis for hemolytic anemia depends on its cause and severity, as well as the underlying health of the affected person. Cases that are caused by medications or infections usually go away quickly. Patients with autoimmune hemolytic anemia usually respond well to corticosteroids or intravenous immune globulin.

The outlook for patients with inherited forms of hemolytic anemia depends on the type of inherited illness and its severity. In general, even patients with more severe forms of these illnesses can expect a longer life span than was previously possible. In some people, a bone marrow transplant may be possible, while other patients hope for newer gene therapies to be developed.

 

Johns Hopkins patient information

Last revised: December 8, 2012
by Brenda A. Kuper, M.D.

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