Serum Protein Electrophoresis (SPEP)

The serum protein electrophoresis (SPEP) test measures specific Reference proteins Opens New Window in the blood to help identify some diseases. Proteins are substances made up of smaller building blocks called Reference amino acids Opens New Window. 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 Reference blood serum Opens New Window 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 Reference hemoglobin Opens New Window, 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 Reference antibodies Opens New Window. They help prevent and fight infection. Gamma globulins bind to foreign substances, such as bacteria or viruses, causing them to be destroyed by the Reference immune system Opens New Window. See a picture of the Reference immune system Opens New Window Reference Opens New Window.

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.

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This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Reference Terms of Use. Reference How this information was developed to help you make better health decisions.