Overview
Serum protein electrophoresis (SPEP) is a laboratory technique that’s used to determine the levels of some types of proteins in a blood sample. There are a number of reasons why a doctor may order this test. SPEP is used to help diagnose and monitor a variety of different diseases or disorders that have abnormal proteins or protein levels. Electrophoresis is not usually used by itself to diagnose a disease. Instead, it’s used along with other laboratory tests to provide more information to help with diagnosis.
One of the best ways to get a better sense of the SPEP test is to look at each word in the name:
Serum
Serum is the liquid part of your blood. Blood appears to be a single substance to the naked eye. However, blood has several components. Both types of blood cells (red and white) and platelets are solids. When these are removed, a liquid is left behind. This is serum.
Protein
Proteins are substances made of small chemicals called amino acids. They have a number of roles:
- They provide structure to the body.
- They help transport nutrients.
- They help the body fight off disease.
Too much or too little protein can cause problems. The five groups of proteins usually considered during an SPEP test are:
- Albumin: This protein transports substances and plays a role in tissue growth and repair.
- Alpha-1 globulins: The major alpha-1 globulin is called alpha-1-antitrypsin, which is produced by the lungs and liver and increases with inflammatory diseases.
- Alpha-2 globulins: This class of protein has many functions in the body and is involved in inflammation.
- Beta globulins: These proteins move substances, support immunity, and increase in number in multiple myeloma and conditions like high cholesterol and atherosclerosis.
- Gamma globulins: These support the immune system and are increased in multiple myeloma, as well as some autoimmune conditions like rheumatoid arthritis and systemic lupus erythematosus.
Electrophoresis
Electrophoresis is a lab technique used to separate groups of proteins in blood serum. This allows them to be measured and analyzed individually. It involves exposing serum placed in a special type of gel to an electric current. This causes the different types of proteins to move and group together. The proteins create separate bands on the gel, which are then analyzed by the laboratory.
Your doctor may recommend SPEP if you are experiencing symptoms of a condition affecting the proteins in your blood serum. These symptoms could include the following:
- unexplained weight loss
- bone pain or frequent fractures
- fatigue
- weakness
- nausea
- constipation
- excessive thirst
- back pain
Some of the conditions that could be causing these symptoms are:
- cancer
- thyroid problems
- diabetes
- anemia
- liver diseases
- malnutrition
- certain autoimmune diseases
- multiple sclerosis
No preparation is needed for the test. When you arrive, a healthcare professional will simply use a needle to take a blood sample. Some people experience mild pain when the needle is inserted. There may be some slight bruising afterward.
The following table shows what most labs would consider normal results for SPEP testing. These values may vary slightly from facility to facility.
| Type of Protein | Amount of Protein (grams/deciliter) |
| albumin | 3.8–5.0 |
| alpha-1 globulin | 0.1–0.3 |
| alpha-2 globulin | 0.6–1.0 |
| beta globulin | 0.7–1.4 |
| gamma globulin | 0.7–1.6 |
The various proteins in the body perform different functions. This means that high or low levels of the five protein types examined during the test can point to different illnesses. Keep in mind that these are just clues. Further investigation will usually be needed to make a definitive diagnosis.
Albumin
| Test Result | Possible Condition(s) |
| Levels higher than normal | Dehydration |
| Levels lower than normal | Kidney or liver disease, a condition involving inflammation, poor nutrition |
Alpha-1 globulin
| Test Result | Possible Condition(s) |
| Levels higher than normal | Disease leading to inflammation (condition may be chronic or acute) |
| Levels lower than normal | Liver disease, congenital emphysema (rare) |
Alpha-2 globulin
| Test Result | Possible Condition(s) |
| Levels higher than normal | Kidney disease, disease leading to inflammation (condition may be chronic or acute) |
| Levels lower than normal | Liver disease, poor nutrition, breakdown of red blood cells |
Beta globulin
| Test Result | Possible Condition(s) |
| Levels higher than normal | Anemia, multiple myeloma, high cholesterol |
| Levels lower than normal | Poor nutrition, liver cirrhosis |
Gama globulin
| Test Result | Possible Condition(s) |
| Levels higher than normal | Rheumatoid arthritis, infection, liver cirrhosis, inflammatory disease, multiple myeloma, lymphoma |
| Levels lower than normal | Immune disorders and deficiencies |
It’s not always obvious what high or low protein levels in the blood serum may mean. A doctor may use the results to make a diagnosis or decide on a course of treatment.
Your doctor may also order more tests. The test may also be performed again in the future. This can help the doctor decide how well therapies and medicines are working.