Peritoneal accumulation of age and peritoneal membrane permeability

Background: In continuous ambulatory peritoneal dialysis (CAPD), the perito neal membrane is continuously exposed:to high-glucose-containing dialysis s olutions. Abnormally high glucose concentration in the peritoneal cavity ma y enhance advanced glycosylation end-product (AGE) formation and accumulati on in the peritoneum. Increased AGE accumulation in the peritoneum, decreas ed ultrafiltration volume, and increased peritoneal permeability in long-te rm dialysis patients have been reported. Aim: The purpose of the study was to evaluate the relation between peritone al membrane permeability and peritoneal accumulation of AGE. Methods: Peritoneal membrane permeability was evaluated by peritoneal equil ibration test (PET) using dialysis solutions containing 4.25% glucose. Seru m, dialysate, and peritoneal tissue levels of AGE were measured by ELISA me thod using polyclonal anti-AGE antibody. Peritoneal biopsy was performed du ring peritoneal catheter insertion [new group (group N), n =18] and removal [long-term group (group LT), n = 10]. Peritoneal catheters were removed du e to exit-site infection not extended into the internal cuff (n = 6) and ul trafiltration failure (n = 4) after 51.6 +/- 31.5 months (13 - 101 months) of dialysis. PET data obtained within 3 months after the initiation of CAPD or before catheter removal were included in this study. Ten patients in gr oup N and 4 patients in group LT were diabetic. Patients in group LT were s ignificantly younger (46.5 +/- 11.1 years vs 57.5 +/- 1.3 years) and experi enced more episodes of peritonitis (3.5 +/- 2.1 vs 0.2 +/- 0.7) than group N. Results: Peritoneal tissue AGE level in group LT was significantly higher t han in group N, in both nondiabetic (0.187 +/- 0.108 U/mg vs 0.093 +/- 0.08 U/mg of hydroxyproline, p < 0.03) and diabetic patients (0.384 +/- 0.035 U /mg vs 0.152 +/- 0.082 U/mg of hydroxyproline, p < 0.03), while serum and d ialysate levels did not differ between the groups in both nondiabetic and d iabetic patients. Drain volume (2600 +/- 237 mL vs 2766 +/- 222 mt, p = 0.0 7) and D-4/D-0 glucose (0.229 +/- 0.066 vs 0.298 +/- 0.081, p < 0.009) were lower, and D-4/P-4 creatinine (0.807 +/- 0.100 vs 0.653 +/- 0.144, p < 0.0 001) and D-1/P-1 sodium (0.886 +/- 0.040 vs 0.822 +/- 0.032, p < 0.0003) we re significantly higher in group LT than in group N. On linear regression a nalysis, AGE level in the peritoneum was directly correlated with duration of CAPD (r = 0.476, p = 0.012), number of peritonitis episodes (r = 0.433, p = 0.0215), D-4/P-4 creatinine (r = 0.546, p < 0.027), and D-1/P-1 sodium (r = 0.422, p = 0.0254), and inversely correlated with drain volume (r = 0. 432, p 0.022) and D-4/D-0 glucose (r = 0.552, p < 0.0023). AGE level in the peritoneal tissue and dialysate were significantly higher in diabetics tha n in nondiabetics in group LT,while these differences were not found in gro up N. Serum AGE level did not differ between nondiabetics and diabetics in either group N or group LT. Drain volume and D-4/D-0 glucose were lower and D-4/P-4 creatinine and D-1/P-1 sodium higher in diabetics than in nondiabe tics in both groups. Conclusion: Peritoneal accumulation of AGE increased with time on CAPD and number of peritonitis episodes, and was directly related with peritoneal pe rmeability. Peritoneal AGE accumulation and peritoneal permeability in diab etic patients were higher than in nondiabetic patients from the beginning o f CAPD.