Densitometric scanning of high-resolution electrophoresis of serum: methodology and clinical application

The recent introduction of high-resolution electrophoresis into many clinical laboratories has expanded the information available about protein abnormalities. While most laboratories interpret high-resolution electrophoresis patterns by direct visual examination of the stained electrophoresis strips, much useful information can be attained by supplemental densitometric scanning of these preparations. In the present report, we detail a method to perform densitometric scanning of high-resolution electrophoresis strips, and compare these results to those performed by standard cellulose acetate electrophoresis. Further, we evaluate the quantitative information by comparing the results from the densitometer scans with nephelometric quantification of specific monoclonal proteins. The present method gives a correlation coefficient of 0.97 when the gamma region densitometric scan is compared to the quantification of IgG by nephelometry in patients with known gamma-migrating IgG monoclonal gammopathies. Further, twofold dilution studies of these specimens showed excellent linearity. By providing objective, reliable, quantitative information, densitometric scanning of high-resolution electrophoresis strips is a useful adjunct to direct visual examination of these specimens.