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Febrile/Cold Agglutinins
Febrile and cold agglutinins are autoantibodies that cause red blood cells to clump together. Learn when your doctor might test your blood for ...

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Febrile and cold agglutinins are types of antibodies. They can cause your red blood cells to clump together. This can prevent your red blood cells from working properly. Agglutinins are associated with several diseases, including hemolytic anemia, lymphoma, and lupus.

A febrile/cold agglutinins test is used to check for the presence of agglutinins in your blood. Sometimes, the febrile agglutinins test is called the fever evaluation test.

What are agglutinins?

Febrile and cold agglutinins are types of autoantibodies. Antibodies are proteins produced by your immune system to combat infection. Autoantibodies are antibodies that attack part of your body instead of pathogens that cause illness or disease.

Febrile and cold agglutinins cause your red blood cells to clump together, or agglutinate. When this happens, your red blood cells can’t perform normally.

Both febrile and cold agglutinins are linked to a variety of illnesses and diseases. They can be present in your blood long after an infection. They can also signal the presence of a disease that hasn’t yet produced symptoms.

You may have cold agglutinins circulating in your bloodstream for years with no ill effects. However, if you need a blood transfusion, cold agglutinins can trigger a fatal reaction.

They can also complicate open-heart surgery or other surgeries in which blood is diverted from your heart. Ordinarily, blood is diverted from your circulatory system and chilled during these types of surgeries. This process is known as hypothermic cardiopulmonary bypass. If you have cold agglutinins in your blood, chilling it causes the agglutinins to attack your red blood cells.

Why is the febrile/cold agglutinins test used?

The febrile/cold agglutinins test is used to diagnose some diseases and infections, including hemolytic anemia. Testing for the presence of these antibodies in your blood can help your doctor diagnose certain illnesses. It can also help them recommend appropriate treatment.

Hemolytic anemia

One of the most common uses of the febrile/cold agglutinins test is to diagnose hemolytic anemia. Ordinarily, healthy red blood cells last for about four months. If you have hemolytic anemia, your red blood cells break down too soon or too often.

If you have anemia, you may experience:

  • lightheadedness
  • irritability
  • a loss of concentration
  • headaches

Other infections

Cold agglutinins may also be present in your blood after you’ve contracted mononucleosis or HIV. This is especially common among children. Among adults, the presence of cold agglutinins can indicate diseases such as lymphoma or chronic lymphoid leukemia. These are types of cancer that affect white blood cells.

Febrile agglutinins are linked to several infectious diseases, including:

  • a Salmonella infection, which is a foodborne infection caused by bacteria
  • brucellosis, which is an infectious disease that can spread from animals to humans
  • tularemia, which is an infectious disease that can spread from animals to humans
  • rickettsial diseases, such as typhus fever and spotted fever

Lymphoma and leukemia may also be associated with febrile agglutinins. However, the febrile agglutinins test is seldom used to diagnose these types of cancer. More specific tests are available to diagnose these diseases.

What does the test involve?

Febrile/cold agglutinins is a diagnostic blood test. A healthcare provider will tie a band around your upper arm to help fill your veins with blood. They’ll insert a small needle into a vein in your arm and collect a sample of your blood. This is a relatively quick and painless process.

They’ll then send the sample of your blood to a lab, where technicians will observe how it reacts to being chilled or heated.


The results or your blood test will be reported as either positive or negative for cold or febrile agglutinins. A medical professional will interpret the results. If you test positive for agglutinins, your doctor will recommend treatment or further testing, depending on the suspected cause of the agglutinins’ presence.

The Takeaway

Your doctor may order a febrile/cold agglutinins test to check for the presence of febrile or cold agglutinins in your blood. This relatively quick and painless procedure can help them diagnose hemolytic anemia and several other conditions. Ask your doctor to learn more about your specific diagnosis, treatment options, and long-term outlook.

Written by: Dale Kiefer
Edited by:
Medically Reviewed by: [Ljava.lang.Object;@6fa0ab56
Published: Jul 5, 2012
Published By: Healthline Networks, Inc.
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