What is a serum protein electrophoresis (SPEP)?

By William Aird

Serum protein electrophoresis (SPEP) is a test that measures the amount of heavy chain monoclonal protein made by myeloma cells. SPEP separates all the proteins in the blood according to their electrical charge. Densitometry is then used to determine the height of the various peaks, resulting in a graph of the results, as shown in various examples below.

Normal SPEP. The Source
Normal SPEP of blood showing a peak in the measurement of albumin (the most plentiful protein in the blood), lower levels of the other proteins, grouped into areas labeled alpha 1 and 2, beta (with two bumps also known as 1 and 2) and gamma, which is where the antibody proteins lie on the graph. From https://www.myeloma.org/monoclonal-protein-tests.

Result for a patient with myeloma. In addition to the spike for albumin, there is another tall spike. The red arrow in the gamma region of the graph indicates this spike. From https://www.myeloma.org/monoclonal-protein-tests.