Types of Cold Agglutinin Disease

Cold agglutinin disease (CAD) is a rare disease in which the immune system attacks the red blood cells in cold temperatures, causing them to clump together and then disintegrate. This leads to anemia, among other symptoms.

CAD is divided into two types — primary CAD and secondary CAD — based on the cause of the disease. The symptoms and treatment are similar for both.

Primary CAD

Patients may be diagnosed with primary CAD if the disease occurs without a known cause. CAD is not inherited, though genetic factors may make a person more likely to develop the disease. CAD is likely to be multifactorial, meaning that more than one factor (genes, environment, etc.) may contribute to its development. Because CAD is an autoimmune disease, patients may develop other autoimmune diseases after developing CAD.

Secondary CAD

Secondary CAD occurs when the immune system’s attack on the red blood cells is caused by an underlying condition. Autoantibodies (antibodies that attack the body’s own cells or tissues) can be produced in autoimmune diseases, and it is thought that patients with one autoimmune disease are more likely to develop another autoimmune disease. In secondary CAD, the autoantibodies against the red blood cells are secondary to another disease, which may itself be an autoimmune disease.

Secondary CAD can also be caused by certain types of viral, parasitic, or bacterial infection or some types of cancer.

Treating the underlying condition often also treats secondary CAD.


Last updated: Aug. 15, 2019


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