Serum Protein Electrophoresis and Its Clinical Applications

*Satish Ramanathan and Chakravarthy Narasimhachar Srinivas*

## **Abstract**

This chapter focuses on the principle of electrophoresis and its utilization in a clinical laboratory. A sincere attempt has been made to discuss about clinical applications of serum protein electrophoresis, throwing light on the significance of serum protein electrophoresis in the management of multiple myeloma. Emphasis has been made on quality assurance in terms of accuracy and precision in electrophoresis to ensure reliability of patient results. A note on issues with lack of standardization of reporting of electrophoresis and an insight into global efforts to standardize the reporting of the assay has been included in this chapter.

**Keywords:** electrophoresis, gamma globulins, polyclonal, oligoclonal, biclonal, myeloma

### **1. Introduction**

Serum protein electrophoresis is an electrophoretic method of separating proteins present in the serum to various fractions based on their molecular weight and electric charges. Electrophoresis had been widely used in clinical medicine for aiding in diagnosis of various clinical conditions like acute and chronic inflammations, monoclonal gammopathies, nephropathy, liver diseases, etc. This chapter discusses the clinical applications of serum protein electrophoresis [1] including the quality control practices and its implications [2].

## **2. Principle**

The separation of proteins by electrophoresis is based on the fact that charged molecules usually migrate through a matrix/medium upon application of an electrical field [3]. The rate at which proteins move in an electric field is determined by a number of factors of the electrophoretic system and the nature of proteins itself. Some factors to mention are the strength of the electric field, temperature of the system, pH of the ions, concentration of buffer etc. [4]. Proteins vary in their size and shape and have the charges determined by the dissociation contents of their amino acids. Smaller proteins usually migrate faster, and larger proteins take a longer time. This physical property of proteins is exploited for its separation by employing the electrophoretic technique.

The most commonly employed variant of electrophoresis for serum protein separation is zone electrophoresis in which the serum proteins are separated into zones or

**Figure 1.** *Sebia Minicap flex piercing capillary electrophoresis.*

fractions and interpreted accordingly [5]. There are several support mediums available for separation of serum proteins including agarose, cellulose acetate, capillary medium etc. [6]; when a capillary medium is used, the technique is known as capillary zone electrophoresis (CZE). Capillary electrophoresis is the preferred method when compared to its competitors including agarose gel electrophoresis due to the following reasons. CZE provides an improved resolution due to the following factors:


Below is an illustration of capillary electrophoresis (Sebia Minicap Flex Piercing) (**Figure 1**). Sebia Minicap Flex Piercing capillary electrophoresis works on the principle of capillary electroendosmosis under high-voltage electric current. The Flex Piercing model of Sebia CZE aids in testing of human blood with capped tubes which in turn eliminates the biohazard xassociated with handling of uncapped samples.
