The presence of abnormal or excessive amounts of proteins, such as immunoglobulins or cryoglobulins, in the blood. Paraproteinemias include amyloidosis, cryoglobulinemia, cryofibrinogenemia, cold IgM antibody disease, light chain disease, monoclonal gammopathy, multiple myeloma, and Waldenstrom’s macroglobulinemia. Plasma exchange therapy, immunomodulating drugs, or specific chemotherapeutic agents are used to treat these disorders.