The Test Sample
What is being tested?
Cold agglutinins are autoantibodies produced by a person's immune system that mistakenly target red blood cells (RBCs). They cause RBCs to clump together when a person is exposed to cold temperatures and increase the likelihood that the affected RBCs will be destroyed by the body. This test detects and measures the amount of cold agglutinins in the blood.
When the presence of cold agglutinins in a person's blood leads to significant RBC destruction, it can cause hemolytic anemia and lead to a low RBC count and hemoglobin. This rare form of autoimmune hemolytic anemia is known as cold agglutinin disease. Cold agglutinin disease may be primary or secondary, induced by some other disease or condition.
Primary cold agglutinin disease typically affects those who are middle age to elderly, and it tends to continue over time (chronic). Secondary cold agglutinin disease may affect anyone and may be acute or chronic, temporary or persistent. It may cause hemolytic anemia to a greater or lesser degree and is associated with a variety of conditions, such as:
- Mycoplasma pneumoniae infections—up to 75% of those affected will have increased cold agglutinins.
- Infectious mononucleosis—more than 60% of those affected will have increased cold agglutinins, but anemia is rare with this infection.
- Some cancers, including lymphoma, leukemia, and multiple myeloma
- Some other bacterial infections, such as Legionnaires disease and syphilis
- Some parasitic infections, such as malaria
- Other viral infections such as HIV, influenza, CMV, EBV, hepatitis C
The cold agglutinin test is not routinely ordered. It is a test that has been available for a long time, but it has become less commonly used as more specific tests for secondary causes, such as Mycoplasma pneumoniae infection, have become available.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm. The sample requires special handling and must be kept within a specific temperature range (not refrigerated) during transport to the laboratory and prior to testing.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.