The Myeloma Alphabet Soup Handbook
Urine Tests

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Immunofixation - Urine

A method (laboratory technique) used to identify proteins in urine. Immunofixation is a laboratory technique that is used to enhance the results of standard protein electrophoresis. With protein electrophoresis, the urine is placed on specially treated paper and exposed to an electric current. The various proteins migrate (move on the paper) to form bands that indicate the relative proportion of each protein fraction. Immunoglobulins (antibodies) appear as a "gamma" band. Immunofixation is a technique to separate this "gamma" band and identify the individual immunoglobulins. It is similar to immunoelectrophoresis but may give more rapid results and is slightly more sensitive. The primary use of immunofixation is the identification and monitoring of monoclonal proteins (that is, IgG, IgM, IgA, lambda light chain, and kappa light chain), including those that are present in multiple myeloma and Waldenstrom's macroglobulinemia. Normal values: No presence of monoclonal immunoglobulins is normal.


Immunoelectrophoresis - Urine

Also known as: Immunoglobulin electrophoresis - urine, or Gammaglobulin electrophoresis - urine, or Urine immunoglobulin electrophoresis (IEP).

A test that detects the presence or absence of immunoglobulins in the urine and assess the qualitative character (polyclonal vs. monoclonal) of the immunoglobulins. Immunoelectrophoresis is a laboratory technique. Electrical charges are used to separate and identify the various immunoglobulins. This test is used to roughly measure the amounts of various immunoglobulins in urine. Most often, this is used as a screening test, particularly in people who have protein in the urine (demonstrated on urinalysis or other test) when urine protein electrophoresis indicates a significant amount of globulin proteins (antibodies). It uses a combination of protein electrophoresis and an antigen-antibody interaction. Protein electrophoresis indicates the presence of immunoglobulins as a group. Immunoelectrophoresis enhances the ability to identify the specific immunoglobulins through the use of antibodies that only react with the proteins of interest. Specific lab technique: Monospecific (that is, specific for only one antigen) antiserum is overlaid on the zone of the electrophoretogram (the paper graph used with protein electrophoresis), which contains the unidentified protein. The presence of a precipitin band indicates that the antigen is present for the monospecific antiserum used Normal values: Normally there is no, or only a small amount, of protein in the urine. When there is protein in the urine, it normally consists primarily of urine albumin


Bence-Jones Protein (quantitative)

Also known as: Immunoglobulin light chains - urine, Urine Bence-Jones protein.

A test to measure the presence of Bence-Jones proteins (free immunoglobulin light chains) in urine. Normally light chains (a small group of antibodies) are produced in excess of heavy chains (a large group of antibodies), so free-light chains are normally present in a small amount in urine. Increases in free-light chains (polyclonal) may occur with increased immunoglobulin synthesis or catabolism (a destructive change in cells). These light chains do not exhibit the thermal characteristics of Bence-Jones proteins (monoclonal free-light chains). Not all monoclonal free-light chains exhibit Bence-Jones behavior, but all are abnormal. Immunofixation is the best test for detecting free monoclonal light chains. Since Bence-Jones proteins are relatively small, they can be filtered by the glomerulus of the nephron. When urine protein is elevated, analysis and other clinical features suggest multiple myeloma, a Bence-Jones proteins test may be ordered. These proteins have an unusual thermal property that allows them to be identified; they precipitate from urine when heated between 45 degrees and 60 degrees C and re-dissolve on boiling. Unequivocal identification is made by immunoelectrophoresis.

Normal values: No presence of Bence-Jones proteins is normal.

Source: Peter Tischler


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Last Updated: 01/02/99