Hemolytic anemia

What is hemolytic anemia?

Anemia is an abnormally low level of red blood cells. Hemolytic anemia occurs when red blood cells are destroyed too quickly.

Red blood cells contain hemoglobin. Hemoglobin is a protein that carries oxygen in the blood. Red blood cells are produced in the bone marrow and then released into the bloodstream. Normally, they live for 110 to 120 days. Old red blood cells 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 can be something wrong with the red blood cells, or the red blood cells are normal but are destroyed by an external process.

Many different problems can cause hemolytic anemia. These include:

• Inherited abnormalities in red blood cell membranes: A red blood cell is like a little balloon filled with fluid. The balloon is the membrane that holds the fluid inside. Defects in the membrane can cause the cells to change shape. Abnormally shaped red blood cells are identified by the spleen as abnormal, and destroyed.
• Inherited enzyme deficiencies inside red blood cells, such as pyruvate kinase (PK) deficiency: Enzymes are proteins. Certain abnormal enzyme levels cause red blood cells to become fragile. They are prone to being destroyed too quickly.
• Hemoglobin disorders: Hemoglobins are proteins that carry oxygen. Some people inherit a gene that makes an abnormal kind of hemoglobin. Hemoglobin disorders include sickle cell anemia and the thalassemias. Hemoglobin disorders can cause red blood cells to be destroyed easily.
• Physical damage to red blood cells: Hemolytic anemia can occur when red blood cells are damaged
  • during heart-lung surgery
  • as they flow near devices placed inside the body, especially artificial heart valves
  • if they are exposed to extreme heat, as in a patient with severe burns
• Autoimmune hemolytic anemia: This occurs when the body's immune system mistakenly destroys its own red blood cells. Autoimmune hemolytic anemia can be caused by
  • autoimmune conditions such as lupus
  • certain types of infections
  • certain medications
• Hypersplenism: The spleen is enlarged and overactive. It traps circulating red blood cells and destroys them before they are old.

In some cases, hemolytic anemia has no clear cause.

Symptoms of hemolytic anemia

Symptoms vary widely. Mild cases may not cause any symptoms. The condition may only be discovered during a routine blood test.

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

• pale skin
• fatigue
• weakness
• dizziness
• lightheadedness
• breathlessness
• yellowing of the skin and eyes
• dark, tea-colored urine.

Diagnosing hemolytic anemia

Your doctor will review your medical history. He or she will ask you to describe your symptoms.

Other questions may include:

• Do you have close relatives with an inherited form of anemia?
• What medications do you take? Were any of them started recently?
• Have you recently had a severe infection?
• Do you have
  • an artificial heart valve
  • a synthetic graft in your blood vessels
  • other implants or prostheses
• Do you have any other symptoms (such as rash or fever) or past medical problems, particularly autoimmune diseases?

During your physical examination, your doctor will look for signs of anemia. These include:

• pale skin and fingernails
• rapid pulse
• heart murmur
• enlarged spleen and liver.

In addition, the examination will look for signs or conditions that can cause hemolytic anemia, such as a rash or arthritis suggestive of lupus.

The exam will be followed by blood tests to:

• measure levels of red blood cells
• look at the size and shape of red blood cells
• measure the hemoglobin level
• determine the number of immature red blood cells. The marrow may pour out immature blood cells in an effort to make up for the anemia.

Your doctor may order tests to check for blood in your stool. This identifies anemia that results from blood loss. Other blood tests check for anemia resulting from a lack of iron or certain vitamins in your diet.

Other tests will depend on the suspected cause of your hemolytic anemia.

Expected duration of hemolytic anemia

How long hemolytic anemia lasts depends on its cause. For example, emolytic anemia caused by a medication or infection is usually temporary. It goes away when the drug is discontinued or the infection is treated.

When the cause is an inherited illness or a chronic disease (such as lupus), the anemia may be chronic or recurrent.

Preventing hemolytic anemia

Hemolytic anemia caused by medication can be prevented by avoiding the drug that is causing the problem.

There is no way to prevent inherited hemolytic anemia. If an inherited anemia runs in your family, you may undergo genetic testing. This can assess your chances of passing it on to your children.

Treating hemolytic anemia

Treatment for hemolytic anemia depends on its cause and severity.

• Inherited abnormalities in red cell membranes: If hemoglobin levels are adequate, you may not need treatment. If hemoglobin levels drop very low, a blood transfusion may be needed. In rare cases, the spleen is removed.
• Inherited enzyme deficiencies inside red cells: Blood transfusions may be necessary to treat severe symptoms. A medication called mitapivat (Pyrukynd) may be helpful for pyruvate kinase deficiency.
• Hemoglobin disorders: Treatment may not be necessary if the illness is mild or does not cause any symptoms. People with more severe forms of thalassemia may require repeated blood transfusions. A medication called luspatercept (Reblozyl) may be recommended. Some patients may be candidates for potentially curative treatments, including stem-cell transplantation.
• Sickle cell anemia may be treated with folic acid supplements, blood transfusions antibiotics (to prevent or treat infections), and hydroxyurea (Hydrea). L-glutamine (by prescription) or crizanlizumab (Adakveo) may be recommended, as they can help reduce the need for transfusions. In some cases, potentially curative treatments may be recommended, including stem-cell transplantation or gene editing. However, these options are not yet widely available.
• Physical damage to red blood cells: This may be treated with folic acid and iron supplements. Blood transfusions may be necessary.
• Autoimmune disease: Treatment depends on the specific cause and its severity. If a drug or an infection is causing autoimmune hemolytic anemia, it may be enough to stop the drug or recover from the infection. For more severe cases, treatment may include:
  • antiviral or antibiotic medication (for infection)
  • corticosteroid medication
  • intravenous immune globulin infusions
  • immunosuppressive drugs
  • removal of the spleen
• Hypersplenism: For severe symptoms, the spleen is removed.

People with severe, chronic hemolytic anemia, especially those with sickle cell anemia or thalassemia, may require multiple blood transfusions. The iron in hemoglobin can accumulate in the body, causing iron overload and organ damage. Drugs called iron chelators, which bind the iron and enhance the body's removal of iron, help prevent organ damage from iron overload. Folic acid is routinely recommended for most people with chronic hemolytic anemia.

When to call a professional

Call your doctor promptly if you develop symptoms of anemia. Also call 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 consider genetic testing before you start a family.

Prognosis

The outlook for hemolytic anemia depends on its cause and severity. The underlying health of the affected person also affects the prognosis.

Cases that are caused by medications or infections usually go away quickly.

People with autoimmune hemolytic anemia usually respond well to treatment, although the underlying condition (such as lupus) may persist, so the hemolytic anemia may recur.

The outlook for people with inherited hemolytic anemias depends on the type of inherited illness and its severity.

Additional info

National Heart, Lung, and Blood Institute (NHLBI)
http://www.nhlbi.nih.gov/

Office of Rare Diseases
http://rarediseases.info.nih.gov/

Cooley's Anemia Foundation
http://www.thalassemia.org/

March of Dimes Birth Defects Foundation
http://www.modimes.org/