Cryoglobulins are abnormal proteins in the blood. If you have cryoglobulinemia (kry-o-glob-u-lih-NEE-me-uh), these proteins may clump together at temperatures below 98.6 F (37 C). These gelatinous protein clumps can impede your blood circulation, which can damage your skin, joints, nerves and organs — particularly your kidneys and liver.

Symptoms usually come and go, and may include:

• Skin lesions. Most people with cryoglobulinemia develop purplish skin lesions on their legs. In some cases, leg ulcers also occur.
• Joint pain. Symptoms resembling rheumatoid arthritis are common in cryoglobulinemia.
• Peripheral neuropathy. Cryoglobulinemia can damage the nerves at the tips of your fingers and toes, causing numbness and other problems.

Different types of cryoglobulinemia have been associated with hepatitis C infection, certain cancers of the blood and autoimmune diseases. Treatment focuses on controlling these underlying diseases and managing symptoms.