Serum Protein Electrophoresis (SPEP)
The serum protein electrophoresis (SPEP) test measures specific proteins in the blood to help identify some diseases. Proteins are substances made up of smaller building blocks called amino acids. Proteins carry a positive or a negative electrical charge, and they move in fluid when placed in an electrical field. Serum protein electrophoresis uses an electrical field to separate the proteins in the blood serum into groups of similar size, shape, and charge.
Blood serum contains two major protein groups: albumin and globulin. Both albumin and globulin carry substances through the bloodstream. Using protein electrophoresis, these two groups can be separated into five smaller groups (fractions):
- Albumin. Albumin proteins keep the blood from leaking out of blood vessels. Albumin also helps carry some medicines and other substances through the blood and is important for tissue growth and healing. More than half of the protein in blood serum is albumin.
- Alpha-1 globulin. High-density lipoprotein (HDL), the "good" type of cholesterol, is included in this fraction.
- Alpha-2 globulin. A protein called haptoglobin, that binds with hemoglobin, is included in the alpha-2 globulin fraction.
- Beta globulin. Beta globulin proteins help carry substances, such as iron, through the bloodstream and help fight infection.
- Gamma globulin. These proteins are also called antibodies. They help prevent and fight infection. Gamma globulins bind to foreign substances, such as bacteria or viruses, causing them to be destroyed by the immune system. See a picture of the immune system.
Each of these five protein groups moves at a different rate in an electrical field and together form a specific pattern. This pattern helps identify some diseases.
Why It Is Done
Serum protein electrophoresis is most often done to:
How To Prepare
You do not need to do anything before you have this test.
Talk to your health professional about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
The health professional drawing blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Apply a gauze pad or cotton ball over the needle site as the needle is removed.
- Apply pressure to the site and then a bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having blood drawn from a vein.
- You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
- In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
- Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.
The serum protein electrophoresis (SPEP) test measures specific proteins in the blood to help identify some diseases. Test results for each protein group are given as a percentage of the total amount of serum protein. To obtain the actual amount of each fraction, a test that measures the total serum protein must also be done.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are usually ready in 2 to 3 days.
Serum protein electrophoresis
|Total serum protein amount in grams per deciliter (g/dL)||Total serum protein amount in SI units grams per liter (g/L)|
| Albumin (adult)|
| Alpha-1 globulin|
| Alpha-2 globulin|
| Beta globulin|
| Gamma globulin|
High values may be caused by:
Low values may be caused by:
- A disease of the immune system, such as systemic lupus erythematosus or rheumatoid arthritis.
- Cancer, such as leukemia, lymphoma, or multiple myeloma.
- Diseases that prevent the intestines from absorbing the nutrients from food, such as sprue or Crohn's disease.
- Heart disease.
- Kidney disease.
- Liver disease.
- Low thyroid levels (hypothyroidism).
- Lung disease, such as emphysema.
- Severe burns.
- Starvation or severe dieting.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
What To Think About
- Electrophoresis on protein in urine may also be done, especially if the results of the serum protein electrophoresis test are abnormal. Normally very little protein is found in urine, but certain diseases (such as multiple myeloma) cause large amounts of protein to leak into the urine.
- Although abnormal protein levels may be found in many conditions (such as kidney disease, chronic liver disease, systemic lupus erythematosus, rheumatoid arthritis, or leprosy), serum protein electrophoresis is usually not done to diagnose these conditions.
- A special test can be done for one of the major parts of the alpha-1 globulin group (called alpha-1 antitrypsin). Alpha-1 antitrypsin inhibits enzymes in the lungs that break down protein. These enzymes can damage normal lung tissue and cause emphysema. People born without the ability to produce alpha-1 antitrypsin often develop severe emphysema at a young age. This condition can be detected by testing them for alpha-1 antitrypsin. For more information, see the topic Alpha-1 Antitrypsin Deficiency Genetic Testing.
- A test for total serum protein is often done at the same time as serum protein electrophoresis. For more information, see the topic Total Serum Protein.
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
|Primary Medical Reviewer||Kathleen Romito, MD - Family Medicine|
|Specialist Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Last Revised||June 11, 2010|