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A paraprotein is an abnormal immunoglobulin fragment detected in the blood or urine that is usually indicative of an underlying malignant disease, such as multiple myeloma. It is often the only by-product of a tumor cell. If these substances are found in the blood or urine and no other malignant diseases have been diagnosed for a period of at least five years, their presence is determined to be a condition called benign paraproteinaemia. During the time prior to the passing of five years, the condition is known as monoclonal gammopathy of uncertain significance (MGUS).
The presence of these immunoglobulin fragments usually points to a B-cell malignancy or lymphoma. They are frequently detected in patients that have a diagnosis of Kaposi’s sarcoma or chronic lymphocytic leukemia. Patients with a compromised immunity, like those that have recently undergone a bone marrow transplant, are likely to have paraproteins in their blood while the immune system rebuilds itself.
Most often, detection leads to a diagnosis of myelomatosis, also called multiple myeloma, which is a cancer of plasma cells. In addition to paraproteins in blood serum or urine, there will be degradation of bone tissue and increased plasma cells within the bone marrow. Normal antibody production is interrupted by the paraproteins, causing a lowered immune defense. It is possible to have a diagnosis of multiple myeloma without the confirmed presence of paraproteins, but it is rare.
With myelomatosis, paraprotein deposits can develop in the kidneys, causing a decrease in renal function. Blood tests will show elevated creatine levels, indicating the renal impairment. Hypercalcemia, which is elevated levels of calcium detected in the bloodstream, can indicate the need to test for the presence of specific substances. The blood calcium levels increase because the destruction of bone cells by osteoclasts releases calcium into the body.
To determine the meaning of the paraprotein detected, a process called protein electrophoresis is performed. The immunoglobulin fragments will show as varying narrow bands on the test strip, enabling the laboratory to decide what type of paraprotein is present in the blood or urine. These tests can give an early indication of the prognosis of the malignant condition.
Persons with paraprotein found in their urine or blood serum will need to have regular blood tests every three months, even if it is determined that their condition is benign. The tests will monitor any increase in the concentration of paraprotein. A change in the concentration or type of paraprotein can be the first indicator of a developing malignant condition.