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
blood serum into groups of similar size, shape, and
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
- 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
- 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
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Apply a gauze pad or cotton ball over the needle site as
the needle is removed.
- Apply pressure to the site and then a