Glycated albumin in serum and dialysate of patients on continuous ambulatory peritoneal dialysis.

1. Chronic use of hyperosmolar glucose solutions in continuous ambulatory peritoneal dialysis may cause glycation of peritoneal structural proteins which could contribute to membrane dysfunction and ultrafiltration failure. To determine whether glycation can occur in the environment of the dialysate, we have carried out studies using albumin as a model protein. 2. Glycated albumin was measured in the serum and dialysate of 46 patients on continuous ambulatory peritoneal dialysis (31 non-diabetic patients, 15 diabetic patients). Dialysate and serum glycated albumin (ranges 1.0-12.7% and 0.9-10.2%, respectively) were related to each other (r = 0.988, P < 0.001), but dialysate glycated albumin was significantly higher than serum glycated albumin (P < 0.0001), with the dialysate to serum glycated albumin ratio being greater than unity in 76% of patients (mean ratio 1.14). This implies either preferential transfer of glycated albumin across the peritoneal membrane or intraperitoneal glycation during the dwell period. 3. In vitro, significant glycation occurred in dialysate during a 6 h incubation period (P < 0.01) at a rate related to the glucose concentration in the dialysate (rs = 0.63, P < 0.05). The glycation rate was not significantly affected (P = 0.05) by factors other than the glucose concentration. 4. Our results demonstrate that protein glycation occurs within the peritoneum during continuous ambulatory peritoneal dialysis. Further studies are required to establish the relationship of glycation of structural proteins in the peritoneal membrane to membrane function.