: Urine analysis for Bence-Jones protein (BJP) has been a test for detection of free light chains (FLC) in the urine for over a century. The method, however, is not standardised. Urine from the same patient is sometimes concentrated by 10-50 fold and sometimes not prior to analysis.
Aim: To assess whether BJP analysed in neat and concentrated urine provides concordant results.
Method: Immunofixation for IgG, IgM, IgA, free kappa (fK) and free lamda (fL) was performed in neat and concentrated (by 10-fold) urines from 44 patients using Hydrogel 9IF, Sebia.
Results: FLC was not detected in both neat and concentrated urines in 36 (86%) patients. The remaining six patients had trace FLC detected only in the concentrated but not the neat urine. Serum FLC results were available from five patients: three had raised fK with abnormal ratios and two raised FLC with normal ratio due to impaired kidney function. The remaining one without serum FLC but had no proteinuria.
Discussion: The findings of this study raise the question whether it is necessary to concentrate the urine for BJP analysis. If this is still required, magnitude of concentrating the urine and how to report the result need to be standardised.
(C) 2015 Royal College of Pathologists of Australasia