Cold/Febrile Agglutinins
Test Description
Agglutinins are antibodies which cause red blood cells to aggregate, or clump.
These antibodies can cause hemolytic anemia. It is important to know which type
of agglutinin is causing the hemolytic anemia so that appropriate therapy can be
initiated.
Cold agglutinins are active at low temperatures. These antibodies, which are
primarily of the IgM type, are most active at temperatures below 37°C, thus the
term “cold” is used. This test is often used to diagnose primary atypical pneumonia
caused by Mycoplasma pneumoniae. Cold agglutinins usually rise within 8 to
10 days after the onset of atypical pneumonia, peak in 12 to 25 days, and decrease
30 days after onset.
Febrile agglutinins are those which are associated with diseases which cause
fever. Such infectious diseases include Brucellosis, rickettsial infections such as
Rocky Mountain spotted fever and typhus, salmonellosis, and tularemia. To test for
febrile agglutinins, a sample of the patient’s serum is mixed with a few drops of prepared
antigens on a slide. If agglutination occurs, antigen is added to serial dilutions
of the patient’s serum until agglutination is no longer noted.
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Normal Values
Cold Agglutinins: No agglutination with titers ≤1:16
Febrile Agglutinins: No agglutination with titers ≤1:80
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Possible Meanings of Abnormal Values
Increased Cold Agglutinins
Hemolytic anemia
Hodgkin’s disease
Infectious mononucleosis
Lymphoma
Malaria
Multiple myeloma
Mycoplasma pneumoniae
Primary atypical pneumonia
Scleroderma
Syphilitic cirrhosis
Viral pneumonia
Increased Febrile Agglutinins
Brucellosis
Rickettsial diseases
Rocky Mountain spotted fever
Salmonellosis
Tularemia
Typhus
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Contributing Factors to Abnormal Values
• Hemolysis of the blood sample may alter test results.
• Drugs which may interfere with the development of cold/febrile agglutinins:
antibiotics.
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Interventions/Implications
Pretest
• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.
Inform the patient that additional blood samples may be needed in 12 to 25 days and
again in 30 days if checking for cold agglutinins and every 3 to 5 days if checking for
febrile agglutinins.
• No fasting is required prior to the test.
Procedure
• A 7-mL blood sample is drawn in a red-top collection tube. The tube is prewarmed to
37°C if checking cold agglutinins and cooled if checking for febrile agglutinins.
• Gloves are worn throughout the procedure.
Posttest
• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued
bleeding.
• Label the specimen and transport it to the laboratory immediately.
• Report abnormal findings to the primary care provider.
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