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. See a picture
of the immune system .
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
Sometimes high levels of cold
agglutinins can destroy red blood cells throughout the body. This condition is
Why It Is Done
The cold agglutinins test may be done
- 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
You do not need to do anything before
you have this test.
How It Is Done
The doctor drawing blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. If the needle is not placed
correctly or if the vein collapses, more than one needle stick may be
- Hook a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then a
How It Feels
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or