Urinary free light chain analysis by the Freelite® immunoassay: a preliminary study in multiple myeloma

Objectives: Evaluate the Freelite® free light chain immunoassay for urine analysis in myeloma. Design and methods Urine specimens from 20 patients were analyzed by Freelite® (The Binding Site) and SDS-agarose gel electrophoresis (Hydragel protéinurie®, Sebia). Results Using the κ/λ ratio, Freelite® was more sensitive than electrophoresis to detect free light chains, but concentration was overestimated in 75% of cases. Conclusions Despite high sensitivity and full automation, Freelite® inaccurately measures monoclonal free light chains in urine.