To help diagnose or monitor conditions that result in abnormal protein production or loss
Protein Electrophoresis Immunofixation Electrophoresis
Proteins are important building blocks of all cells and tissues. They form the structural part of most organs and make up enzymes and hormones that regulate body functions. Body fluids contain many different proteins that serve diverse functions, such as transport of nutrients, removal of toxins, control of metabolic processes, and defense against invaders. Protein electrophoresis is a method for separating these proteins based on their size and electrical charge.
When the proteins in body fluids are separated by electrophoresis, they form a characteristic pattern of bands of different widths and intensities, reflecting the mixture of proteins present. This pattern is divided into five fractions, called albumin, alpha 1, alpha 2, beta, and gamma. In some cases, the beta fraction is further divided into beta 1 and beta 2.
Albumin, which is produced in the liver, accounts for about 60% of the protein in the blood. "Globulins" is a collective term used to refer to proteins other than albumin. With the exception of the immunoglobulins and some complement proteins, most of the globulins are also produced in the liver.
Immunofixation electrophoresis (IFE) is a method used to identify abnormal bands seen on serum, urine, or cerebrospinal fluid (CSF) protein electrophoresis, in order to determine which type of antibody (immunoglobulin) is present.
The major plasma proteins and their functions are listed according to their electrophoretic group (the visible band that they are part of) in the table below titled Protein Groups.
How is the sample collected for testing?
Protein electrophoresis is typically done on serum (the fluid portion of blood) and urine samples. A blood sample is obtained by inserting a needle into a vein in the arm. Urine samples may either be collected as a random sample (not timed) or a 24-hour urine sample. Cerebrospinal fluid (CSF) is collected by a spinal tap (inserting a needle into the spine to withdraw spinal fluid).
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
How is it used?
Protein electrophoresis is used to identify the presence of abnormal proteins, to identify the absence of normal proteins, and to determine when different groups of proteins are present in unusually high or low amounts in blood or other body fluids.
Proteins do many things in the body, including the transport of nutrients, removal of toxins, control of metabolic processes, and defense against invaders.
Protein electrophoresis separates proteins based on their size and electrical charge. This forms a characteristic pattern of bands of different widths and intensities on a test media and reflects the mixture of proteins present in the body fluid evaluated. The pattern is divided into five fractions, called albumin, alpha 1, alpha 2, beta, and gamma. In some cases, the beta fraction is further divided into beta 1 and beta 2.
Immunofixation electrophoresis (IFE) can be used as needed to further identify abnormal bands, in order to determine which type of antibody (immunoglobulin) is present.
Alterations to the usual appearance of the patterns formed can help in the diagnosis of disease. The presence of an abnormality on a protein electrophorectic pattern is seldom diagnostic in itself. Instead, it provides a clue. Follow-up testing is then usually performed, based on that clue, to try to identify the nature of the underlying disease.
When is it ordered?
Protein electrophoresis may be ordered as a follow up to abnormal findings on other laboratory tests or as an initial test in evaluating a person's symptoms. Once a disease or condition has been diagnosed, electrophoresis may be ordered at regular intervals to monitor the course of the disease and the effectiveness of treatment. Some examples of when an electrophoresis test may be ordered are listed below.
Serum electrophoresis may be ordered:
- As a follow up to abnormal findings on other laboratory tests, such as total protein and/or albumin level, elevated urine protein levels, elevated calcium levels, or low white or red blood cell counts
- When symptoms suggest an inflammatory condition, an autoimmune disease, an acute or chronic infection, a kidney or liver disorder, or a protein-losing condition
- When a health practitioner is investigating symptoms that suggest multiple myeloma, such as bone pain, anemia, fatigue, unexplained fractures, or recurrent infections, to look for the presence of a characteristic band (monoclonal immunoglobulin) in the beta or gamma region; if a sharp band is seen, its identity as a monoclonal immunoglobulin is typically confirmed by immunofixation electrophoresis.
- To monitor treatment of multiple myeloma to see if the monoclonal band is reduced in quantity or disappears completely with treatment
Urine protein electrophoresis may be ordered:
- When protein is present in urine in higher than normal amounts to determine the source of the abnormally high protein; it may be used to determine whether the protein is escaping from the blood plasma (suggesting compromised kidney function) or is an abnormal protein coming from a different source (such as a plasma cell cancer like multiple myeloma).
- When multiple myeloma is suspected, to determine whether any of the monoclonal immunoglobulins or fragments of monoclonal immunoglobulin are escaping into the urine; if a sharp band suggestive of a monoclonal protein is observed, its identity is typically confirmed by immunofixation electrophoresis.
CSF protein electrophoresis may be ordered:
- To search for the characteristic banding seen in multiple sclerosis; the presence of multiple distinct bands in the CSF (that are not also present in serum) are referred to as oligoclonal bands. Most people with multiple sclerosis, as well as some other inflammatory conditions of the brain, have such oligoclonal bands.
- To evaluate people having headaches or other neurologic symptoms to look for proteins suggestive of inflammation or infection
Immunofixation electrophoresis may be ordered:
- When an abnormal band suggestive of a monoclonal immunoglobulin is seen on either a serum or a urine electrophoresis pattern
What does the test result mean?
Protein electrophoresis tests give a health practitioner a rough estimate of how much of each protein fraction is present and whether any abnormal proteins are present. The value of immunofixation electrophoresis is in the identification of the presence of a particular type of immunoglobulin. The laboratory report may include an interpretation of the results.
Certain conditions or diseases may be associated with decreases or increases in various serum proteins, as reflected below.
Protein May be decreased in: May be increased in: Albumin Alpha 1 globulin
- Congenital emphysema (alpha-1 antitrypsin deficiency, a rare genetic disease)
- Severe liver disease
Alpha 2 globulin
- Severe liver disease
- Kidney disease (nephrotic syndrome)
- Acute or chronic inflammatory disease
- Variety of genetic immune disorders
- Secondary immune deficiency
- Polyclonal, antibody produced by or derived from different plasma cells:
- Monoclonal, antibody produced by or derived from a single type (clone) of plasma cell:
- Multiple myeloma
- Waldenstrom's macroglobulinemia
Usually there is very little protein in urine. Typically, if a significant amount of protein is present, it appears in one of three main patterns.
- Normally, the glomeruli prevent protein from leaking into the urine. When the glomeruli are damaged, albumin and other plasma proteins may leak through and be detected in the urine.
- Normally, some very small proteins can pass through the glomeruli but are removed from the urine by the tubules. When the tubules are damaged, these proteins will appear in the urine.
- Some other small proteins are not normally present in significant amounts in serum, for example, free light chains, myoglobin and hemoglobin. When they are present in the serum, they can pass through the glomeruli and appear in the urine.
- Presence of multiple bands in the gamma region (oligoclonal bands) that are not present in serum is indicative of multiple sclerosis.
- Presence of higher than normal polyclonal immunoglobulins, antibodies produced and secreted by many different plasma cells, suggests an infection.
Is there anything else I should know?
Immunizations within the previous six months can increase immunoglobulins as can drugs such as phenytoin (Dilantin), procainamide, oral contraceptives, methadone, and therapeutic gamma globulin.
Aspirin, bicarbonates, chlorpromazine (Thorazine), corticosteroids, and neomycin can affect protein electrophoresis results.
Is electrophoresis used for anything else?
If I have an abnormal monoclonal immunoglobulin in my blood, does it mean that I have multiple myeloma or some other type of cancer?
Not necessarily. Monoclonal protein production is most commonly due to monoclonal gammopathy of undetermined significance (MGUS). Most people with MGUS have a benign course, but they must continue to be monitored regularly with a serum protein electrophoresis test, or sometimes a free light chain test, depending on which monoclonal protein is being produced. Some of these people may develop multiple myeloma after a number of years.
What are free light chains and how are they related to immunoglobulins?
Immunoglobulins are molecules composed of four protein chains: two identical light chains, either kappa or lambda light chains, and two identical heavy chains of which there are several types. These proteins are produced by plasma cells in the bone marrow. A particular plasma cell only produces one type of immunoglobulin. It uses the protein chains as component parts to assemble immunoglobulins, antibodies that target specific threats to the body. The chains that are used to form the immunoglobulins are said to be "immunoglobulin-bound." Normally, there is also a slight excess of kappa and lambda light chains produced. Low levels of these "free" light chains can be detected in the blood and urine with a free light chain test, and ratios between the kappa and lambda free light chains can be evaluated. For more information, see the article on Serum Free Light Chains.
What are Bence Jones proteins?
They are free immunoglobulin light chains that are found in the urine.
What is Tamm-Horsfell protein?
The term Tamm-Horsfell refers to a glycoprotein that is a normal component of urine. It is more commonly called uromodulin. It is produced by the kidney and is the most abundant protein in normal urine.
On This Site
Elsewhere On The Web
American Cancer Society: How is multiple myeloma diagnosed?
National Cancer Institute: Multiple myeloma/Other plasma cell neoplasms
Multiple Myeloma Research Foundation: What is multiple myeloma?
Mayo Clinic: Amyloidosis
National Kidney and Urologic Diseases: Amyloidosis and Kidney Disease
National Human Genome Institute: Electrophoresis