Urine protein electrophoresis and immunofixation electrophoresis supplement one another in characterizing proteinuria.

Urine protein electrophoresis (UPE) is often considered to have limited usefulness in evaluating proteinuria that is not associated with gammopathies. Unusual protein bands that are detected by UPE are commonly characterized by immunofixation electrophoresis (IFE). In this paper, electrophoretic gel patterns are shown to illustrate the greater sensitivity of IFE, compared to UPE. However, UPE remains useful for three applications: (1) UPE provides distinctive patterns that can indicate the source of proteinuria and is useful in assessing renal diseases that are independent of gammopathy; (2) combined use of UPE and IFE can avoid misinterpretations and repeated analyses of urine proteins, and (3) UPE can be used in conjunction with IFE to improve the quantitation of Bence-Jones proteinuria (BJP).