What Is PEP Lab & Diagnostic Testing?

Protein electrophoresis (PEP) tests refer to lab tests used to screen and diagnose a variety of conditions. PEP tests may be performed on samples of blood serum (sometimes called SPEP) or urine (sometimes called UPEP).


Laboratory specialists analyse PEP tests by putting the urine or blood sample on special paper and sending an electrical current through the sample. The electrical current causes proteins to visibly band together.


SPEP labs measure several protein groups, such as alpha-1 globulin and gamma globulin, as well as total protein. Abnormal results indicate different conditions, depending on the protein or protein group. For example, decreased total protein may indicate malnutrition or cirrhosis. High levels of alpha-1 globulin proteins may indicate cancer or an inflammatory disease.


UPEP labs measure levels of albumin and globulins, two types of protein, in the urine. High levels of protein in the urine may indicate a variety of disorders, such as decreased kidney function, kidney failure, urinary tract infection or diabetic nephropathy.


Many medicines, including corticosteroids, salicylates, tolbutamide and chlorpromazine, may cause inaccurate PEP lab results. Do not stop taking prescription drugs without asking your doctor first.