Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1210 page)

SERUM PROTEIN ELECTROPHORESIS/IMMUNOFIXATION

   Definition

   Serum protein electrophoresis (SPE) is a method of physical separation of protein molecules based on their charge. Changes in both quality and nature of proteins determined by SPE allow clinicians to detect and monitor various pathophysiologic states. SPE, enhanced by follow-up procedures like protein quantification and immunofixation (IF), provides the best tools for general screening of human health state. The monoclonal gammopathies are a group of disorders characterized by the proliferation of a single clone of plasma cells that produces an immunologically homogeneous protein commonly referred to as a paraprotein or monoclonal protein (M-protein). SPE is usually done by the agarose gel electrophoresis or by the capillary zone electrophoretic method. It is the recommended method for the detection of an M-protein. The resulting M-protein, if found, can then be quantitated by means of a densitometer tracing of the gel. In the electrophoretic methodologies (agarose or capillary zone), proteins are classified by their final position after electrophoresis is complete into five general regions: albumin, alpha-1, alpha-2, beta, and gamma. The various immunoglobulin classes (IgG, IgA, IgM, IgD, and IgE) are usually of gamma mobility and make up most of the gamma region, but they may also be found in the beta-gamma and beta regions and may occasionally extend into the alpha-2 globulin area.

   Other names: serum protein electrophoresis (SPEP).

   
Normal range:

   SPE:

   Albumin: 3.5–5.0 g/dL

   Alpha-1 globulin: 0.1–0.3 g/dL

   Alpha-2 globulin: 0.5–1.0 g/dL

   Beta globulin: 0.5–0.9 g/dL

   Gamma globulin: 0.6–1.4 g/dL

   IF: no monoclonal protein detected

   Use