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.
The major plasma proteins and their functions are listed according to their electrophoretic group (the visible band that they are part of) in a table titled Protein Groups.
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.
Follow-up tests may include, for example, albumin, immunoelectrophoresis, serum free light chains, quantitative immunoglobuins, alpha-1 antitrypsin or cryoglobulins.
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.
Serum electrophoresis
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 |
- Malnutrition and malabsorption
- Pregnancy
- Kidney disease (especially nephrotic syndrome)
- Liver disease
- Inflammatory conditions
- Protein-losing syndromes
|
|
| Alpha 1 globulin |
- Congenital emphysema (alpha-1 antitrypsin deficiency, a rare genetic disease)
- Severe liver disease
|
- Acute or chronic inflammatory diseases
|
| Alpha 2 globulin |
- Malnutrition
- Severe liver disease
- Hemolysis
|
- Kidney disease (nephrotic syndrome)
- Acute or chronic inflammatory disease
|
| Beta globulin |
|
- High blood cholesterol (hypercholesterolemia)
- Iron deficiency anemia
- Some cases of multiple myeloma or monoclonal gammopathy of unknown significance (MGUS)
|
| Gamma globulin |
- Variety of genetic immune disorders
- Secondary immune deficiency
|
- Polyclonal, antibody produced by or derived from different plasma cells:
- Chronic inflammatory disease
- Rheumatoid arthritis
- Lupus
- Cirrhosis
- Chronic liver disease
- Acute and chronic infection
- Recent immunization
- Monoclonal, antibody produced by or derived from a single type (clone) of plasma cell:
- Malignancy
- Multiple myeloma
- Lymphoma
- Waldenstrom's macroglobulinemia
|
Urine electrophoresis
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 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.
CSF electrophoresis
- 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.
Immunofixation electrophoresis
- Identifies the type of immunoglobulin protein(s) present in monoclonal bands on a protein electrophoresis pattern; typically immunofixation determines the presence of a heavy chain (IgG, IgM or IgA) and a light chain (kappa or lambda). For more about this, see Common Questions #3.
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.
