Coomb's test

A Coomb's test is a test for antibodies or complement (another protein/enzyme that works with antibodies) attached to the surface of red blood cells. It is possible to do a general test for these without knowing the specific antibody due to similarities between most of the antibodies that attach to red blood cells.

When a bacteria, a drug or anything else attaches itself to red blood cells (rbcs) the body tries to attack it with antibodies as it would if it wasn't attached to rbcs. This can lead to lysis of the red cells, which is usually referred to as immune mediated hemolytic anemia (IMHA). So a positive Coomb's test indicates a strong possibility of IMHA. This test can also be positive for other reasons, including ehrlichia, demodecosis and severe infections. It is possible to have a negative Coomb's test and still have IMHA, as well.

Even though the most commonly run Coomb's test is kind of a general screen, it is possible to test for specific types of antibodies, if desired. Sometimes this helps in establishing a prognosis if IMHA is suspected.