Background. Increased levels of oxidized proteins have been reported in the serum of patients with end-stage renal disease, though little is known regarding the oxidized protein content of the dialysate in patients on peritoneal dialysis (PD) and no information is available as to how this may correlate with important clinical and laboratory variables, including abnormal peritoneal membrane function. In this study we attempted to identify oxidized proteins in the dialysate of patients on PD using western blot analysis, and examined the relationship between these proteins and the function of the peritoneal membrane and other clinical and laboratory variables.

Methods. Peritoneal dialysate and serum samples were obtained from 18 patients on PD, and western blot analysis using an antibody to oxidized protein was carried out with reprobing for albumin. Oxidized protein/albumin ratios were determined and compared with various clinical and laboratory variables including peritoneal equilibration test results.

Results. Oxidized protein/albumin ratios were higher in the dialysate of patients who were high/high average transporters compared to low/low average transporters. Oxidized protein ratios were also found to be higher in the dialysate of patients who had diminished urine output as a reflection of loss of residual renal function. Negative correlations were noted between oxidized protein ratios in the dialysate and serum albumin levels and creatinine clearance.

Conclusions. Higher levels of oxidized protein in the dialysate appear to be correlated with high/high average peritoneal membrane transport characteristics and may be related to loss of residual renal function. These preliminary findings suggest that it is plausible that oxidized proteins in the dialysate might play a contributory role in complications including membrane damage and ultrafiltration failure in patients on PD.