What is Autoimmune Hemolytic Anemia (AIHA)?
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Autoimmune hemolytic anemia (AIHA) is a rare form of anemia caused by a malfunction of the immune system.
Anemia happens when the body does not have enough red blood cells. When someone has AIHA, their immune system creates proteins (called antibodies) that attack and destroy the body's own red blood cells.
AIHA is a complicated condition that affects people in different ways. Some of the most common symptoms are fatigue, weakness, dizziness, and shortness of breath.
It is not always possible to completely cure AIHA, but the condition can be managed. Treatment can help stop the destruction of red blood cells and improve symptoms for most people.
The Role of Red Blood Cells in AIHA
Red blood cells are responsible for transporting oxygen to all the cells of the body. A lack of red blood cells to carry oxygen can leave a person tired, short of breath, and looking pale. The medical term for a lack of red blood cells is anemia.
Red blood cells contain an important protein called hemoglobin. Hemoglobin contains iron, which binds easily to oxygen. Hemoglobin also gives blood its red color.
Hemoglobin in the red blood cells attaches to oxygen molecules at the point where the lungs come into contact with the bloodstream. After delivering oxygen to the body's cells, the red blood cells pick up carbon dioxide and carry it back to the lungs to be exhaled.
Red blood cells play a role in helping the immune system defend against invading bacteria or viruses. Red blood cells can release substances that cause the blood vessels to dilate when necessary.
The Types of Autoimmune Hemolytic Anemia (AIHA)
AIHA is classified in a number of different ways. Figuring out what kind of AIHA a person has helps doctors determine the best treatment for each case.
In general, AIHA is categorized as either primary or secondary. AIHA is also classified as warm-antibody AIHA or cold-antibody AIHA according to the optimal temperature at which the antibodies destroy red blood cells
Primary AIHA
Primary AIHA is AIHA that has no apparent cause. About half of all cases of AIHA are primary. This type of AIHA is more likely than secondary AIHA to be asymptomatic (causing no symptoms). Primary AIHA is also more likely than secondary to be life-threatening. Another name for primary AIHA is idiopathic AIHA. Idiopathic is a medical term meaning “of unknown cause.”
Secondary AIHA
Secondary AIHA, also called acquired AIHA, is AIHA caused by an underlying health condition. Health conditions commonly associated with secondary AIHA include autoimmune disorders (for example, lupus or rheumatoid arthritis) and blood cancers (such as lymphocytic leukemia or lymphoma). Secondary AIHA may also be caused by infection or a reaction to a drug.
What is the difference between warm and cold autoimmune anemia?
Immunoglobulin G (IgG) is the antibody associated with most cases of warm-antibody AIHA. Cold-antibody AIHA is most likely to be caused by the immunoglobulin M (IgM) antibody.
Warm-Antibody Autoimmune Anemia
Red blood cells are destroyed at normal body temperature
70% to 80% of AIHA cases
Affects men and women equally
The antibody is almost always IgG
50% of cases are primary, 50% are secondary
The Secondary kind of Warm-Antibody anemia is likely caused by an autoimmune or lymphoproliferative disorder
Cold-Antibody Autoimmune Anemia
Red blood cells are destroyed at temperatures below normal body temperature
Up to 20% of AIHA cases
Older women more likely to be affected
The antibody is usually IgM
Most often associated with secondary causes
The secondary cause is most likely infection or a lymphoproliferative disorder
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References:
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