Inaccuracies in 24-Hour Urine Testing for Monoclonal Gammopathies

Abstract

Urine protein electrophoresis (UPEP) has been used for many years to assess for the presence of urinary free kappa and free lambda light chains, alternatively known as Bence-Jones proteins. In 2009, the International Myeloma Working Group recommended serum free light chain analysis for free kappa and free kappa light chains instead of UPEP in the screening algorithm for multiple myeloma, but 24-h UPEP remained recommended for monitoring response to treatment for patients with light chain disease not measurable with serum protein electrophoresis. Creatinine clearance (CrCl) is another method to assess renal function. CrCl, UPEP, and urine protein measurements rely on accurate 24-hour urine collections.