Cold agglutinin disease is a rare autoimmune disorder in which autoantibodies produced by a person's immune system mistakenly target and destroy RBCs, causing hemolytic anemia. These autoantibodies are cold-reacting and can cause signs and symptoms related to anemia after an affected person is exposed to cold temperatures. This disease may be classified as either primary or secondary, triggered by an infection or other condition.
This test is performed on a series of dilutions of a blood sample that are prepared in test tubes and then cooled to a low temperature, typically 4°C (39.2°F). Each dilution is then evaluated for clumped RBCs, with the results reported as a titer – the highest dilution that shows detectable clumping. When cold agglutinins are present, RBC clumping is visible while the sample is cold and disappears when the sample is warmed. The exact temperature at which this will occur will vary as some cold agglutinins will react over a wider temperature range than others.
The result of a cold agglutinin test is typically reported as a titer, such as 1:64 or 1:512. A higher number means that there are more autoantibodies present. Higher titers of autoantibodies and those that react at warmer temperatures are associated with hemolytic anemia and worse symptoms.
The degree of red blood cell (RBC) hemolysis and hemolytic anemia will vary from person to person and with each episode of cold exposure. Some conditions, such as infectious mononucleosis, are frequently associated with elevated cold agglutinins but rarely associated with anemia.
Sometimes a cold agglutinin test may be run at one or more additional temperatures that are lower than body temperature but warmer than 4°C, such as performed at 30°C (86°F) to determine the point at which the RBCs start to clump. This information may be important for someone who has chronically elevated cold agglutinins and is being considered for a surgery that involves body cooling.
A cold agglutinin test may rarely be ordered to identify increased cold agglutinins if someone has a condition that has been linked to secondary cold agglutinin disease, such as infectious mononucleosis or a Mycoplasma pneumoniae infection. Since the test is not specific for these conditions, it is not typically ordered to diagnose or monitor them.
This article was last reviewed on September 27, 2013. | This article was last modified on September 27, 2013.
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