A cold agglutinins blood test is done to check for conditions that cause the body to make certain types of antibodies called cold agglutinins. Cold agglutinins are normally made by the immune system in response to infection. They cause red blood cells to clump together (agglutinate) at low temperatures.
Healthy people generally have low levels of cold agglutinins in their blood. But lymphoma or some infections, such as mycoplasma pneumonia, can cause the level of cold agglutinins to rise.
Higher-than-normal levels of cold agglutinins generally do not cause serious problems. Sometimes, high levels of cold agglutinins can cause blood to clump in blood vessels under the skin when the skin is exposed to the cold. This causes pale skin and numbness in the hands and feet. The symptoms go away when the skin warms up. In some cases, the clumped blood cells can stop the flow of blood to the tips of the fingers, toes, ears, or nose. This is like frostbite and can cause tissue damage. In rare cases, it can cause gangrene.
Sometimes high levels of cold agglutinins can destroy red blood cells throughout the body. This condition is called autoimmune hemolytic anemia.
Why It Is Done
The cold agglutinins test may be done to:
See whether high cold agglutinin levels are causing autoimmune hemolytic anemia.
Find pneumonia caused by mycoplasma. Over half of people with pneumonia caused by mycoplasma develop an increase in cold agglutinin levels in their blood within a week of being infected. Newer tests for mycoplasma pneumonia have replaced the cold agglutinins blood test.
How To Prepare
In general, there's nothing you have to do before this test, unless your doctor tells you to.
How It Is Done
A health professional uses a needle to take a blood sample, usually from the arm.
How It Feels
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
High titres of cold agglutinins may be caused by infections, such as pneumonia caused by mycoplasma, mononucleosis, hepatitis C, or other viral infections.
High titres of cold agglutinins can cause symptoms when a person is exposed to cold temperatures. These symptoms can include numbness, burning, pain, or pale skin of the fingertips, toes, ears, or nose. Very high titres can mean you have a higher chance of developing blood clots (thromboses) when exposed to cold temperatures.
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