Protein electrophoresis - serum

Definition
This test roughly quantitates the various protein fractions in the serum portion of a blood sample. See also Immunoelectrophoresis - serum; Immunofixation - serum; Serum globulin electrophoresis.

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 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.

Individual proteins, with the exception of albumin, are not usually measured. However, protein fractions or groups ARE measured. The levels of protein fractions can be roughly measured by measuring the total serum protein and multiplying by the relative percentage of each component protein fraction.

Lipoprotein electrophoresis is a type of protein electrophoresis that is focused on determining the amount of lipoproteins (materials such as LDL cholesterol).

How to prepare for the test

The health care provider may advise you to discontinue drugs that could interfere with the test. DO NOT discontinue any medication without discussing with your health care provider.

You may be advised to fast for 4 hours before a lipoprotein electrophoresis test.

For infants and children:
The preparation you can provide for this test depends on your child’s age and previous experience. For general information regarding how you can prepare your child, see the following topics:

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

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 separated into albumin and globulins. In other words, total protein = albumin + globulin. Albumin is the protein of highest concentration in the serum. It carries many small molecules, but 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-1, alpha-2, beta, and gamma globulins. These can be separated and quantitated in the laboratory by electrophoresis and densitometry.

The alpha-1 fraction or portion includes alpha-1 anti-trypsin (see Alpha-1 antitrypsin) and thyroxine binding globulin (see T3, T4, RT3U). The alpha-2 fraction contains haptoglobin, ceruloplasmin, HDL, and alpha-2 macroglobulin.

In general, alpha-1 and alpha-2 proteins levels increase in the presence of inflammation. The beta fraction includes transferrin (see Iron - serum), plasminogen (see Factor VIII assay), and beta-lipoproteins (see LDL). The gamma fraction includes the various types of antibodies (immunoglobulins M, G, and A).

Normal Values

     
  • Total protein: 6.4 to 8.3 g/dL  
  • Albumin: 3.5 to 5.0 g/dL  
  • Alpha-1 globulin: 0.1 to 0.3 g/dL  
  • Alpha-2 globulin: 0.6 to 1.0 g/dL  
  • Beta globulin: 0.7 to 1.2 g/dL  
  • Gamma globulin: 0.7 to 1.6 g/dL

What abnormal results mean

Decreased total protein may indicate:

     
  • Malnutrition  
  • Nephrotic syndrome  
  • Gastrointestinal protein-losing enteropathy

Increased alpha-1 globulin proteins may indicate:

     
  • Chronic inflammatory disease (for example, Rheumatoid Arthritis, SLE)  
  • Acute inflammatory disease  
  • Malignancy

Decreased alpha-1 globulin proteins may indicate:

     
  • Alpha-1 antitrypsin deficiency

Increased alpha-2 globulin proteins may indicate:

     
  • Acute inflammation  
  • Chronic inflammation

Decreased alpha-2 globulin proteins may indicate:

     
  • Hemolysis

Increased beta globulin proteins may indicate:

Decreased beta globulin proteins may indicate:

     
  • Congenital coagulation disorder  
  • Consumptive coagulopathy  
  • Disseminated intravascular coagulation

Increased gamma globulin proteins may indicate:

     
  • Multiple Myeloma  
  • Chronic inflammatory disease (e.g., Rheumatoid Arthritis, SLE)  
  • Hyperimmunization  
  • Acute infection  
  • Waldenstrom’s macroglobulinemia  
  • Chronic liver disease

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

Special considerations

Drugs that can affect the measurement of total proteins include chlorpromazine, corticosteroids, isoniazid, neomycin, phenacemide, salicylates, sulfonamides, and tolbutamide.

Veins and arteries vary in size from one patient to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 3, 2012
by Levon Ter-Markosyan, D.M.D.

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