| Monoclonal gammopathy | |
| Synonyms: | paraproteinemia |
Monoclonal gammopathy, also known as paraproteinemia, is the presence of excessive amounts of myeloma protein or monoclonal gamma globulin in the blood. It is usually due to an underlying immunoproliferative disorder or hematologic neoplasms, especially multiple myeloma. It is sometimes considered equivalent to plasma cell dyscrasia. The most common form of the disease is monoclonal gammopathy of undetermined significance.
See main article: article and Plasma cell dyscrasia. Causes of paraproteinemia include the following:
These are characterized by the presence of any abnormal protein that is involved in the immune system, which are most often immunoglobulins and are associated with the clonal proliferation of lymphocytes.[1]
When a paraproteinemia is present in the blood, there will be a narrow band, or spike, in the serum protein electrophoresis because there will be an excess of production of one protein.[2]
There are two large classes of blood proteins: albumin and globulin. They are generally equal in proportion, but albumin is much smaller than globulin, and slightly negatively charged, which leads to an accumulation at the end of the electrophoretic gel. The globulins separate out into three regions on the electrophoretic gel, which are the α band, the β band, and the γ band.
Paraproteinemias may be categorized according to the type of monoclonal protein found in blood:
The three types of paraproteins may occur alone or in combination in a given individual. Note that while most heavy chains or whole immunoglobulins remain within blood vessels, light chains frequently escape and are excreted by the kidneys into urine, where they take the name of Bence Jones protein.
It is also possible for paraproteins (usually whole immunoglobulins) to form polymers by aggregating with each other; this takes the name of macroglobulinemia and may lead to further complications. For example, certain macroglobulins tend to precipitate within blood vessel with cold, a phenomenon known as cryoglobulinemia. Others may make blood too viscous to flow smoothly (usually with IgM pentamer macroglobulins), a phenomenon known as Waldenström macroglobulinemia.
The most common type of paraproteinemia is monoclonal gammopathy of undetermined significance (MGUS). Another form, monoclonal gammopathy of renal significance (MGRS) results in kidney damage and chronic kidney disease due to the effects of monoclonal immunoglobulins.[5]