Cold agglutinin disease is a rare type of anemia, a condition that occurs when your body doesn't have enough red blood cells. It's usually noticed when your body temperature drops below normal.

The coombs test is one of the tests used to determine the cause of hemolytic anemia. The direct coombs test looks for antibodies attached to red blood cells. Antibodies can be produced by the body, caused by disease, or from a blood transfusion.