Cold agglutinins; Weil-Felix reaction; Widal test; Warm agglutinins; Agglutinins
Agglutinins are antibodies that cause the red blood cells to clump together.
This article describes the blood test that is used to measure the level of these antibodies in the blood.
There is no special preparation.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing where the needle was inserted.
This test is done to diagnose certain infections and find the cause of hemolytic anemia (a type of anemia that occurs when red blood cells are destroyed). Knowing whether there are warm or cold agglutinins can help explain why the hemolytic anemia is occurring and direct treatment.
Normal results are:
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
An abnormal (positive) result means there were agglutinins in your blood sample.
Warm agglutinins may occur with:
Cold agglutinins may occur with:
Risks are slight but may include:
If a disease linked to cold agglutinin is suspected, the person needs to be kept warm.
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Review Date: 5/4/2022
Reviewed By: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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