Cryoglobulinemia

Cryoglobulinemia is a medical condition in which the blood contains large amounts of cryoglobulins - proteins (mostly immunoglobulins themselves) that become insoluble at reduced temperatures. This should be contrasted with cold agglutinins, which cause agglutination of RBCs. Cryoglobulins typically precipitate at temperatures below normal body temperature (37 degrees Celsius) and will dissolve again if the blood is heated. Cryoglobulinemia can be associated with various diseases such as multiple myeloma and hepatitis C infection.
Cryoglobulinemia at Wikipedia