Serum globulin electrophoresis
Serum globulin electrophoresis is a form of protein electrophoresis that examines the globulin proteins.
How the test is performed
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to swell with blood.
A needle is inserted into the vein, and the blood is collected in an airtight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
For an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
Electrophoresis is a laboratory technique. The blood serum (the fluid portion of blood) is placed on specially treated paper and exposed to an electric current. The various proteins migrate (move on the paper) to form bands that indicate the relative proportion of each protein fraction.
How to prepare for the test
Fast for 4 hours before the test. The health care provider may advise you to withhold drugs that can interfere with the test (see special considerations). DO NOT discontinue any medications without discussing with your health care provider.
For infants and children:
The preparation you can provide for this test depends on your child’s age and previous experience. For specific information regarding how you can prepare your child, see the following topics:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- Schoolage test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is performed when the amount of globulin proteins are of particular interest. Identification of the various types of globulins (globulin electrophoresis) can be useful in the diagnosis of various disorders.
Proteins are made from amino acids and are important constituents of all cells and tissues. There are many different kinds of proteins in the body with many different functions, for example, enzymes, some hormones, hemoglobin (oxygen transport), LDL (cholesterol transport), fibrinogen (blood clotting), collagen (structure of bone and cartilage), and immunoglobulins (antibodies).
Serum proteins are grossly separated into albumin and globulins. In other words, total protein = albumin + globulin. Albumin is the protein of highest concentration in the serum (plasma, the fluid portion of blood, is serum plus clotting proteins). Albumin is a carrier of many small molecules, but it is also of prime importance in maintaining the oncotic pressure of the blood (that is, keeping the fluid from leaking out into the tissues).
Globulins are roughly divided into alpha, beta, and gamma globulins. These can be separated and quantitated in the laboratory by electrophoresis and densitometry. The gamma fraction includes the various types of antibodies (immunoglobulins M, G, and A).
- Serum globulin: 2.0 to 3.5 g/dL
- IgM component: 75 to 300 mg/dL
- IgG component: 650 to 1850 mg/dL
- IgA component: 90 to 350 mg/dL
What abnormal results mean
Increased gamma globulin proteins may indicate:
- Multiple myeloma
- Chronic inflammatory disease (for example, rheumatoid arthritis and SLE)
- Acute infection
- Waldenstrom’s macroglobulinemia
What the risks are
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
- Multiple punctures to locate veins
Drugs that can affect the measurement of serum proteins include chlorpromazine, corticosteroids, isoniazid, neomycin, phenacemide, salicylates, sulfonamides, and tolbutamide.
by Brenda A. Kuper, M.D.