LAUSR

Background Residual renal function is closely linked to quality of life, morbidity and mortality in dialysis patients. Beta-trace protein (BTP), a low molecular weight protein, has been suggested as marker of residual renal function, in particular in patients on hemodialysis. We hypothesized that BTP also serves as a marker of residual renal function in pertioneal dialysis patients. Methods In this study 34 adult patients on peritoneal dialysis were included. BTP, creatinine, cystatin C and urea concentrations were analyzed simultaneously in serum and dialysate to calculate renal and peritoneal removal of the analytes. Results In peritoneal dialysis patients with residual diuresis, mean serum BTP was 8.16 mg/l (SD ± 4.75 mg/l). BTP correlated inversely with residual diuresis (r s  = − 0.58, p  < 0.001), residual creatinine clearance (Cl Cr ) (r s  = − 0.69, p  < 0.001) and total urea clearance (Cl urea ) (r s  = − 0.56, p  < 0.001). Mean peritoneal removal of BTP was 3.36 L/week/1.73m 2 (SD ± 1.38) and mean renal removal 15.14 L/week/1.73m 2 (SD ± 12.65) demonstrating a significant renal contribution to the total removal. Finally, serum BTP inversely correlated with alterations in residual diuresis ( r  = − 0.41, p  = 0.035) and renal creatinine clearance over time ( r  = − 0.79, p  =  p  < 0.001). Conclusion BTP measurement in the serum may be a simple tool to assess residual renal function in peritoneal dialysis patients.