Cold Agglutinins

Agglutinins are antibodies that cause red blood cells to form a clump called rouleaux formation at low temperatures. This is an immune reaction to an infection. High levels of agglutinins can impede blood flow to the extremities when exposed to cold, resulting in tissue damage. It can cause hemolytic anemia. The cold agglutinins test measures the level of agglutinins in a blood sample.

Why the Test Is Performed

The test is performed to screen for hemolytic anemia and the underlying cause for pneumonia.

Before Administering the Test

Assess if the patient has:

  • Taken penicillin or cephalosporins
  • Measles, malaria, congenital syphilis, pneumonia, chickenpox, anemia, infectious mononucleosis, cirrhosis, or multiple myeloma, since these can produce a false positive test result

How the Test Is Performed

A sample of blood is taken from the patient's vein. The patient will experience a tight feeling when the tourniquet is tightened, a pinch or nothing at all when the needle is inserted into the vein, and pressure when a gauze pad is pressed against the insertion site to stop bleeding. It can take up to 10 minutes for bleeding to stop if the patient is taking anticoagulants (aspirin, coumadin). A small bruise might appear at the insertion site, which could become swollen following this test. This is called phlebitis. Applying a warm compress several times a day will reduce the swelling.

Teach the Patient

Prior to testing, explain to the patient why the blood sample is taken and that the healthcare provider may request the patient stop taking penicillin or cephalosporins for 2 weeks prior to the test.

Understanding the Test Results

Test results are available quickly. The laboratory determines normal values based on calibration of testing equipment with a control test. Test results are reported as high, normal, or low based on the laboratory's control test. Results are reported as a titer. Atiter specifies how much of the sample of blood is diluted with saline before antibodies are no longer detected. The titer is reported as a ratio of parts of the blood sample and saline. The higher the second number of the ratio, the greater the number of antibodies in the blood sample. Normal cold agglutinins titer range is below 1 to 40 (1:40). A high cold agglutinins titer may indicate pneumonia, hepatitis C, cirrhosis, infectious mononucleosis, rheumatoid arthritis, malaria, hemolytic anemia, multiple myeloma, lymphoma, cytomegalovirus, scleroderma, or risk for thromboses.

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