Coagulation refers to a blood clot that forms because of an open wound or from cholesterol within blood vessels. Agglutination occurs when an antibody forms in the blood, and bacteria, blood cells and other cells clump together to fight infections.
Blood clots also form when blood fails to flow properly in the body. Blood clots stop bleeding in open wounds, but clots can cause a heart attack or stroke when they form within a blood vessel.
Agglutinins are antibodies that form as an immune reaction, such as when someone catches a cold. Conditions such as lymphoma and mycoplasma pneumonia cause elevated cold agglutinins in normally healthy people.