Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

Protein Electrophoresis
Immunofixation Electrophoresis

Print this article
Share this page:
Also known as: Serum Protein Electrophoresis; Protein ELP; SPE; SPEP; Urine Protein Electrophoresis; UPE; UPEP; IFE; CSF Protein Electrophoresis
Formal name: Protein Electrophoresis; Immunofixation Electrophoresis

The Test Sample

What is being tested?

Proteins are important building blocks of all cells and tissues. They form the structural part of most organs and make up enzymes and hormones that regulate body functions. Body fluids contain many different proteins that serve diverse functions, such as transport of nutrients, removal of toxins, control of metabolic processes, and defense against invaders. Protein electrophoresis is a method for separating these proteins based on their size and electrical charge.

When the proteins in body fluids are separated by electrophoresis, they form a characteristic pattern of bands of different widths and intensities, reflecting the mixture of proteins present. This pattern is divided into five fractions, called albumin, alpha 1, alpha 2, beta, and gamma. In some cases, the beta fraction is further divided into beta 1 and beta 2.

Albumin, which is produced in the liver, accounts for about 60% of the protein in the blood. "Globulins" is a collective term used to refer to proteins other than albumin. With the exception of the immunoglobulins and some complement proteins, most of the globulins are also produced in the liver.

Immunofixation electrophoresis (IFE) is a method used to identify abnormal bands seen on serum, urine, or cerebrospinal fluid (CSF) protein electrophoresis, in order to determine which type of antibody (immunoglobulin) is present.

The major plasma proteins and their functions are listed according to their electrophoretic group (the visible band that they are part of) in a table titled Protein Groups.

How is the sample collected for testing?

Protein electrophoresis is typically done on serum (the fluid portion of blood) and urine samples. A blood sample is obtained by inserting a needle into a vein in the arm. Urine samples may either be collected as a random sample (not timed) or a 24-hour urine sample. Cerebrospinal fluid (CSF) is collected by a spinal tap (inserting a needle into the spine to withdraw spinal fluid).

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.