What is an immunofixation test and what is it used for?

The immunofixation test is useful for differentiating disorders related to the proportions of proteins in the blood, especially when multiple myeloma is suspected. Know how it is done.

Written and verified by the doctor Mariel mendoza on 02 October, 2021.

Last update: October 02, 2021

The immunofixation test is also known as immunofixation test, electrophoresis protein or proteinogram. Is used for measure the levels of different proteins in the blood and identify variations in their proportions.

The immunofixation test separates proteins into subgroups, based on their molecular weight and electrical charge. The subgroups consist of albumin, alpha-globulins, beta-globulins, and gamma-globulins. Measuring the subgroups makes it possible to detect different disorders in quantitative and qualitative variations.

The test is done on a blood sample. The risks of taking the sample are those associated with the puncture, such as bleeding at the puncture site, hematoma due to accumulation of blood under the skin and a feeling of light-headedness.

Subsequently, the sample is centrifuged, obtaining the liquid part of the blood that does not contain blood cells or clotting factors, called serum. This is used for the immunofixation test.

Basis of the immunofixation or electrophoresis test

Electrophoresis is a technique that allows to separate subgroups of proteins from blood serum, depending on its physical characteristics (molecular weight and electrical charge). The serum is placed on a special paper and exposed to an electric current; this allows the mobilization of proteins and their grouping.

Clustering on paper creates separate bands, zones, or patterns, which are analyzed by chemical methods. The immunofixation test fixes proteins with targeted antibodies and stains them. This is what creates the separate patterns, in which you can see peaks or valleys, depending on the concentrations.

These banding patterns are specific for different diseases. However, the test allows a qualitative assessment. When quantitative assessment is required, it is performed with other tests, such as nephelometry and turbimetry.

A blood sample is sufficient to do the electrophoresis.

Separation of protein subgroups in the immunofixation test

The degree of separation will depend on the technique used at the laboratory. The most common is cellulose acetate, which allows the identification of five subgroups: albumin, alpha-1-globulins, alpha-2-globulins, beta-1-globulins, beta-2-globulins, and gamma-globulins.

In addition, it allows the albumin / globulin ratio to be determined and total proteins to be measured by colorimetry. Reports can also be read using a densitometer.

1. Albumin measurement

Albumin is the highest proportion protein in the blood, representing 58-74% of total proteins. It is synthesized in the liver and depends proportionally to the consumption of proteins.

The increase in albumin may be due to acute dehydration or in cases of patients receiving parenteral nutrition. While it can be decreased in conditions in which there is an increase in its destruction or a reduction in its synthesis.

This last phenomenon is associated with the following causes:

  • Chronic inflammatory diseases: rheumatoid arthritis or pelvic inflammatory disease.
  • Liver disease: acute or chronic hepatitis, alcoholism.
  • Enteropathy protein loser.
  • Nutritional diseases: malnutrition or intestinal malabsorption.
  • Renal glomerulus diseases: nephrotic syndrome and nephritic syndrome.
  • Third spaces: edema and ascites.

2. Measurement of alpha-globulins

In the case of alpha-1-globulin and alpha-2-globulin, increased levels are associated with any inflammatory event (which can be acute or chronic). While decreased levels are linked to liver disease or malnutrition and malabsorption.

3. Measurement of beta-globulins

Increased levels of beta-globulins are associated with chronic anemia, especially associated with iron deficiency, multiple myeloma or hypercholesterolemia. Decreased levels are related to liver disease or reduced protein intake.

4. Measurement of gamma-globulins

Gamma-globulins are represented by immunoglobulins or antibodies, predominantly of type G, A, D and E. These are part of the immune system and protect against diseases.

The immunofixation test can identify not only the presence of immunoglobulins, but also the type of abnormal immunoglobulin. Its alteration is called gammopathy.

The main utility of the immunofixation test is the identification of monoclonal immunoglobulins. These have a spike appearance in the bands, which is called peak M and it is associated with different types of blood cell cancer (multiple myeloma and Waldenström macroglobulinemia).

In the case of monoclonal augmentation, there is an overproduction of a single immunoglobulin that conditions a decrease in the proportion of the rest that is not affected. In up to 60% of cases it corresponds to the diagnosis of multiple myeloma or solitary plasmacytoma.

The polyclonal increase in immunoglobulins can be associated with chronic inflammatory diseases (systemic lupus erythematosus, rheumatoid arthritis), autoimmune diseases, different types of cancer (leukemias and lymphomas), sarcoidosis and chronic infections.

Decreased gamma-globulins or hypogammaglobulinemia is associated with acquired immunodeficiency syndrome (AIDS), chronic steroid use, nephrotic syndrome, and neoplastic diseases such as leukemia.

Increased or decreased gamma globulins are indicative of diseases that are often serious.

Indications for the immunofixation test

The immunofixation test is ordered in cases of abnormal levels of total or fractionated proteins. Also due to the suspicion of a condition that affects the concentration of blood proteins or causes loss of them, such as the suspicion of multiple myeloma and Waldenstrom's macroglobulinemia. In the presence of proteinuria (loss of protein in the urine), this test is also required.

The immunofixation test is useful for the diagnosis of disorders in the proportions of proteins in the blood and is the first method at the time of suspicion of multiple myeloma. It is widely distributed and easily accessible.