At a glance
Also known as
Serum protein electrophoresis; SPEP; urine protein electrophoresis; UPEP; immunoelectrophoresis; immunofixation electrophoresis; IFE
Why get tested?
To help diagnose and monitor multiple myeloma and a variety of other conditions that affect protein absorption, production and loss as seen in severe organ disease and altered nutritional states
When to get tested?
If you have an abnormal total protein or albumin level or if your doctor suspects that you have a condition that affects protein concentrations in the blood and/or causes protein loss through the urine
A blood sample drawn from a vein in your arm; sometimes a or
Test preparation needed?
What is being tested?
Protein electrophoresis is a method for separating the found in blood (serum) or urine. During the test, an electric current is used to move the proteins across a thin layer of agarose gel. The distances that individual proteins travel depend on their size, shape and electrical charge.
These separated proteins may be detected by the use of a dye that binds to (stains) all of the proteins and reveals a characteristic pattern of bands. Each band indicates the presence of a particular protein, while the size of the band is a rough indication of the quantity. This pattern of bands is converted into a visual graph, showing vertical spikes or peaks where there is a lot of protein and smaller peaks or valleys where there is less. A newer method called capillary zone electrophoresis (CZE) separates proteins by passing them through a long, thin column, producing a graph that is very similar to the one made by running the protein through an agarose gel.
Specific proteins of interest can be identified after the electrophoresis step by first fixing them in the gel with antibodies, then washing away all the other proteins prior to staining. This procedure is called immunofixation electrophoresis (IFE). A slightly different method, immunoelectrophoresis, was used in the past to identify specific proteins. However, this technique has been largely superseded by IFE because IFE is easier to perform and interpret.
Serum proteins are separated into five or six major groupings by protein electrophoresis. These fractions are called albumin, alpha 1, alpha 2, beta and gamma (the beta fraction is sometimes divided into beta 1 and beta 2). Albumin, which is produced in the liver, forms its own group and accounts for about 60% of the protein in the blood. is a collective term used to refer to proteins other than albumin. With the exception of the and some complement proteins, most of the globulins are produced in the liver. These groups are described more fully in the table, .
The bands seen on protein electrophoresis form characteristic patterns. Alterations to these patterns are associated with a variety of different diseases and conditions. For example in multiple myeloma (a cancer of certain types of white blood cells called plasma cells), the uncontrolled growth and division of a malignant plasma cell leads to the production of large amounts of a single type of ().
In contrast to other proteins in serum, which are typically of a single type, antibodies (immunoglobulins) must differ from each other to be able to recognise bacteria, viruses and other 'foreign' substances. Each time the body is exposed to a virus, for example, one plasma cell replicates and makes a group (or clone) of plasma cells to produce antibody to eliminate it.
Since our total immunoglobulin represents antibody made by many clones, we refer to it as a polyclonal pattern. When there is a cancer of plasma cells, only one type of antibody is produced, termed a monoclonal pattern. This abnormal protein can be seen as a characteristic band on the electrophoresis gel.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm. Sometimes a or is required.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.