Also known as: Serum protein electrophoresis, urine protein electrophoresis, IFE
Name: Protein electrophoresis and immunofixation electrophoresis
Related tests: Albumin, Immunoelectrophoresis, Total protein
Why is the test done?
To help diagnose and monitor multiple myeloma and other conditions involving the absorption, production and loss of proteins, as seen in some serious organ diseases and in nutritional disorders.
When is it done?
If you have abnormal total protein or albumin levels, or if the doctor suspects a condition involving the build-up of proteins in the blood or their loss in the urine.
What samples are required?
A blood sample taken from a vein in the arm; sometimes it is done on a urine sample or a 24-hour urine collection.
What is being tested?
Protein electrophoresis is a method of separating the proteins in the blood (serum) or urine. During the test, an electric current is used to move the proteins across a gel slab such as agar. The distance each protein travels depends on its size, shape and electrical charge. The proteins can be detected with dyes that bind to all proteins and show a characteristic pattern of bands. Each band indicates the presence of a particular protein, while the size of the band is closely related to its amount. This pattern of bands is converted into a graph, which shows tall peaks where there is a high concentration of a single protein and smaller peaks where there is less. A newer method called capillary zone electrophoresis (CZE) separates the proteins by passing them through a long capillary, giving results very similar to agarose gel electrophoresis.
Proteins of particular interest can be identified by first fixing them with antibodies and then washing away the other proteins before staining. This procedure is called immunofixation electrophoresis (IFE). A slightly different method, immunoelectrophoresis, was used in the past to identify specific proteins. This technique has now largely been replaced by IFE, which is easier to perform and interpret.
Electrophoresis separates the serum proteins into five or six groups. 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, produced in the liver, makes up almost 60% of the serum proteins. “Globulins” include all the other proteins. With the exception of the immunoglobulins and some complement proteins, most globulins are produced in the liver. These classes are described in more detail in the Protein classes table.
The bands seen in protein electrophoresis form a characteristic pattern. Changes in this pattern are associated with a variety of diseases and conditions. For example, in multiple myeloma (a cancer of plasma cells), the uncontrolled growth of malignant plasma cells leads to the production of a high concentration of a single type of monoclonal immunoglobulin. Unlike other serum proteins, which are typically of a single type, antibodies (immunoglobulins) differ from one another so that they can recognise bacteria, viruses and other foreign substances. Each time the body is exposed to a virus, for example, a plasma cell multiplies and creates a group (clone) of plasma cells to produce targeted antibodies. Since our immunoglobulins are the antibodies produced by many different clones, we call them polyclonal. When there is a cancer of the plasma cells, a single antibody is produced, called a monoclonal protein. This abnormal protein can be seen as a band on the electrophoresis gel
How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?
How is it used?
Electrophoresis is used to identify the presence or absence of abnormal proteins and to show when different groups of proteins are increased or decreased in serum or urine. It is often requested to detect and identify monoclonal proteins (overproduction of a specific immunoglobulin). Protein electrophoresis and immunofixation are requested to detect, diagnose and monitor the course and treatment of conditions associated with these abnormal proteins, such as multiple myeloma and related diseases.
Normally only minimal amounts of protein are excreted in the urine. Moderate or large amounts indicate a kidney problem. The main reason for requesting urine protein electrophoresis and immunofixation is to detect the production of monoclonal proteins. This protein may be found in both serum and urine or only in urine. An example is Bence Jones protein, which is the free light chain of antibodies. (Antibodies are normally made up of four parts, two heavy chains and two light chains. Sometimes, in multiple myeloma, one or the other is produced, or they are produced in excess.) The small size of Bence Jones protein means that it is filtered by the kidneys and excreted in the urine.
Urine protein electrophoresis may also be requested to diagnose the cause and assess the severity of kidney damage or disease. This damage or disease may be caused by diabetes, chronic inflammation, autoimmune disease or cancer. Electrophoresis is not needed to investigate a small or moderate loss of protein due to temporary conditions such as a urinary tract infection or acute inflammation.
When is it requested?
Protein electrophoresis may be requested when the doctor wants to investigate symptoms suggesting multiple myeloma, such as bone pain, anaemia, tiredness, unexplained fractures and recurrent infections. It may also be requested to follow up other laboratory results, such as abnormal total protein or albumin levels, high levels of protein in the urine, a high calcium level, or a low white or red blood cell count. Immunofixation is requested when protein electrophoresis shows an abnormal band that may be associated with immunoglobulins.
Electrophoresis is requested when the doctor suspects a disease or condition causing the production of monoclonal proteins. Once a disease has been diagnosed, electrophoresis may be requested at regular intervals to monitor its course and the effectiveness of treatment. As the disease progresses, the amount of protein increases; with treatment it falls. The production of monoclonal proteins may be secondary to cancers such as multiple myeloma, but also to monoclonal gammopathy of undetermined significance (MGUS), which causes no symptoms. Most patients with MGUS have a benign course, but they must be monitored regularly in case they develop multiple myeloma years later.
Protein electrophoresis may also be requested when symptoms suggest inflammation, autoimmune disease, acute or chronic infection, kidney or liver abnormalities or protein loss, even if total protein or albumin appear normal. Urine electrophoresis is requested when protein is found in the urine or the doctor suspects monoclonal proteins.
What does the test result mean?
Protein electrophoresis and immunofixation give an estimate of the amount of each type of protein present. The value of protein electrophoresis lies in the proportions between the individual proteins and in the pattern of the various subclasses shown in the resulting graph. The value of immunofixation lies in identifying the presence of a particular type of immunoglobulin.
For example, certain conditions or diseases may be associated with a fall or rise in some serum proteins, as described below:
Albumin decreased: in malnutrition and malabsorption, pregnancy, kidney disease (especially nephrotic syndrome), liver disease, inflammation and protein-losing conditions.
Increased: in dehydration.
Alpha-1 globulin decreased: in congenital emphysema (alpha-1 antitrypsin deficiency, a rare genetic disease) and in severe liver disease.
Increased: in acute and chronic inflammatory diseases.
Alpha-2 globulin decreased: in hyperthyroidism or severe liver disease, and haemolysis (breakdown of red blood cells).
Increased: in kidney disease (nephrotic syndrome) and acute or chronic inflammatory diseases.
Beta globulins decreased: in malnutrition and cirrhosis
Increased: in high cholesterol, iron deficiency anaemia, some cases of multiple myeloma and MGUS.
Gamma globulins decreased: in various immune disorders and in secondary immunodeficiencies.
Increased: Polyclonal: chronic inflammatory disease, rheumatoid arthritis, systemic lupus erythematosus, cirrhosis, chronic liver disease, acute and chronic infections, recent immunisations.
Monoclonal: in Waldenström’s macroglobulinaemia, multiple myeloma and monoclonal gammopathies of undetermined significance (MGUS).
Is there anything else I should know?
Aspirin, bicarbonates, chlorpromazine (Thorazine), corticosteroids and neomycin can affect electrophoresis.
Albumin:
this protein can be considered normal if its percentage is between 59.1 and 69.3 and its amount is between 3.70 and 5.30 grams per decilitre of blood.
If its percentage or amount is higher than normal, the other proteins have correspondingly decreased and
the liver is therefore working well. However, this finding is of little clinical relevance to the doctor.
If its percentage falls but not its amount, the other proteins have correspondingly increased, and this may prompt the doctor to investigate further for inflammatory diseases or a worrying disease such as myeloma.
If both its percentage and its amount fall, the liver is not producing proteins properly. This change usually indicates liver cirrhosis, a disease characterised by severe, irreversible damage to the liver cells with consequent loss of liver function.
Alpha-1 globulins:
this protein can be considered normal if its percentage is between 2 and 3.5 and its amount is between 0.14 and 0.30 grams per decilitre of blood.
A fall in its percentage or amount has no clinical significance.
If its percentage or amount is higher than normal, this indicates inflammation or an infection in the body.
Alpha-2 globulins:
this protein can be considered normal if its percentage is between 6.1 and 11.2 and its amount is between 0.41 and 0.90 grams per decilitre of blood.
A fall in its percentage or amount has no clinical significance.
If its percentage or amount is higher than normal, this, as with alpha-1 globulins, indicates inflammation or an infection in the body.
Beta globulins:
this protein can be considered normal if its percentage is between 6.30 and 12.1 and its amount is between 0.56 and 1 gram per decilitre of blood.
A fall in its percentage or amount has no clinical significance.
If its percentage or amount is higher than normal, this may be a sign of anaemia, because the beta globulins include transferrin, which rises when iron in the body is low.
Gamma globulins:
this protein can be considered normal if its percentage is between 9.8 and 20 and its amount is between 0.68 and 1.5 grams per decilitre of blood.
A fall in its percentage or amount indicates reduced antibody production, mostly due to a lack of stimuli (bacteria) rather than disease. It can therefore be interpreted as a sign of good health.
If its percentage or amount is higher than normal, this is a sign of:
polyclonal disease, when the increase involves all types of antibody; this is typical of acute or chronic inflammation, so it indicates inflammation or an infection;
or monoclonal disease, if the antibody-producing cells go out of control and produce a single type of antibody, always the same, in large amounts and in a disorderly way. When the monoclonal increase is very high, it may indicate a worrying disease such as “plasmacytoma” or “multiple myeloma”, a malignant blood cancer characterised by this overproduction of antibodies, or a “benign monoclonal gammopathy”, a fairly common condition that in some cases is associated with infectious or chronic diseases and may disappear on its own, and in other cases is of uncertain significance and should be kept under observation.
1. Why does my doctor request electrophoresis even though my total protein and albumin are normal?
2. Is electrophoresis used for other purposes?
1. Why does my doctor request electrophoresis even though my total protein and albumin are normal?
Protein electrophoresis may be requested because there can be an abnormality even when total protein and albumin are normal. This is because the body tries to keep protein levels constant, so it may reduce or increase the production of other proteins to make up for a deficiency or overproduction. The doctor may request urine electrophoresis when protein is found in the urine, because protein may be lost even when blood levels are stable.
2. Is electrophoresis used for other purposes?
Yes, whenever proteins or other molecules need to be separated. DNA electrophoresis, for example, is used to study the genetic make-up of plants, animals and humans.