Hemoglobin interference with urinary Bence Jones protein analysis on electrophoresis

Two cases are described which show that on urine protein electrophoresis a paraprotein owing to hemoglobin cannot be distinguished from a Bence Jones protein. A simple method is described for confirming the presence of hemoglobin: a densitometric scan of the electrophoretogram at 415 nm, in which hemoglobin absorbs in a band coincident with the restriction. Furthermore, it is shown that other serum proteins, elevated levels of bilirubin, and Bence Jones protein do not interfere with this detection system.