Unexpected migration of free light chains in urinary protein electrophoresis.

Urinary protein electrophoresis analysis (UPE) is an essential investigation for the study of abnormal proteins in urines. The interpretation of this analysis must be comprehensive and relevant. Indeed, UPE is often requested by clinicians and may have an important impact in patient's management. This paper presents two cases with free light chains showing unexpected electrophoretic migration which can lead to the misinterpretation of results. This article helps biologists to keep in mind the interest of UPE among the several analyses useful in the laboratory.