Urinary gamma-glutamyl transferase-to-creatinine ratio as an indicator of tubular function in Bence Jones proteinuria.

Increased urinary gamma-glutamyl transferase (GGT) activity suggests early renal tubular damage. The aim of this study was to evaluate the urinary GGT activity as a marker of renal injury in different types of Bence Jones Proteinuria (BJP). One hundred and three individuals with BJP were included in the study. Urinary GGT activity, urinary GGT-to-creatinine ratio and urinary protein-to-creatinine ratio were studied. Urine samples were tested by immunofixation agarose gel electrophoresis. Total urinary excretion of kappa and lambda light chains were measured by nephelometric method. There were no significant differences in demographic characteristics of the patients in Lambda BJP, Kappa BJP and Control groups. GGT-to-creatinine ratio of the Lambda BJP group was significantly higher than Kappa BJP group and controls (p = 0.018 and 0.002, respectively). There was no correlation between the quantitative kappa and lambda BJP and urinary GGT-to-creatinine ratio. Our data have demonstrated that urinary GGT-to-creatinine ratio could be a tubular damage marker of lambda light chain proteinuria.