Cryoglobulins are abnormal antibodies produced by plasma cells and dissolved in the blood. When cooled below normal body temperature, cryoglobulins form large collections of solid particles (precipitates). When warmed to normal body temperature, they re-dissolve.

The formation of cryoglobulins (cryoglobulinemia) is uncommon. In most instances, an underlying disorder causes people to form cryoglobulins. These disorders include cancers such as macroglobulinemia and chronic lymphocytic leukemia, autoimmune disorders such as systemic lupus erythematosus (lupus), and infections by such organisms as hepatitis C virus. Rarely, a cause for the formation of cryoglobulins cannot be found.

Precipitates of cryoglobulins can trigger inflammation of blood vessels (vasculitis), which causes various symptoms, such as bruises, joint aches, and weakness. The vasculitis may damage the liver and kidneys. In some people, the damage may progress to liver failure and kidney failure and can be fatal.

People with cryoglobulinemia may also be very sensitive to cold or develop Raynaud syndrome, in which the hands and feet become very painful and turn white when chilled.

Avoiding cold temperatures helps prevent vasculitis. Treating the underlying disorder may reduce the formation of cryoglobulins. For example, using interferon alpha to treat hepatitis C virus infection helps reduce formation of cryoglobulins. Removal of a large amount of plasma (the liquid part of blood) plus plasma transfusions (plasma exchange) may help, especially when combined with interferon.