Description
Cryoglobulins are a group of circulating proteins specifically immunoglobulins (i.e., IgG, IgM, IgA or light chains), that clump together (precipitate) from serum, plasma or urine upon exposure to cold and dissolve when warmed.They may be present in small quantities in the blood of some healthy people but are most frequently associated with abnormal protein production and a variety of diseases and conditions. This test detects and measures the relative quantity of cryoglobulins in the blood.
Precipitated cryoglobulins can slow the flow of blood and block small blood vessels. The presence of large amounts of cryoglobulins in the blood, called cryoglobulinemia, can cause symptoms such as bruising, rashes, joint pain, weakness, and Raynaud phenomenon – pain, paleness, bluing, numbness, tingling and coldness in the fingers and toes with exposure to cold. (These symptoms can also occur in people who do not have cryoglobulinemia.) Cryoglobulins can cause tissue damage that leads to skin ulcers and, in severe cases, to gangrene. They can activate the immune system, leading to the deposit of immune complexes in tissues, and cause inflammation, bleeding, and clotting that can affect circulation in organs such as the kidneys and liver.
There are three types of cryoglobulinemia:
Type I, which consists of a monoclonal immunoglobulin – a single type of protein that is produced by an abnormal cloned cell. This type is often seen in people with myeloma or lymphoma.
Type II, which consists of a mixture of monoclonal and polyclonal immunoglobulins. This type is often seen in people with hepatitis C or other viral infections.
Type III, which consists of polyclonal immunoglobulins. This type is often seen in people with autoimmune diseases.
Initial testing does not distinguish between these three types of cryoglobulins, but the proteins involved can be determined through subsequent protein electrophoresis testing.This test determines the presence and quantity of cyroglobulins in the blood which is an abnormal blood protein. When the temperature decreases the protein in the blood starts to clump and symptoms start to take place.Individuals who experience bruising, skin ulcers, fatigue, weakness and muscle pain are recommended for this test.No test preparation is usually needed. An 8-hour fast before sample collection may be instructed to minimize the potential for turbidity (cloudiness) in the sample due to triglycerides.If the cryoglobulin test is positive, then it will be followed with protein electrophoresis and immunofixation electrophoresis (IFE) testing to determine which type(s) of protein are present as cryoglobulins and which type of cryoglobulinemia the person has.
Most people who have cryoglobulinemia are chronically infected with hepatitis C virus (HCV), although not everyone with HCV (fewer than 3%) will develop cryoglobulinemia.Avoiding contact with cold objects and exposure to cold items can help prevent or minimize symptoms.A number of treatment options are available. These include Corticosteroids or other immunosuppressors, Plasmapheresis or Newer biologic medications, such as rituximab (Rituxan), which is an artificial antibody that can prevent the protein forming clumps.
