Association between inflammation and changes in residual renal function and peritoneal transport rate during the first year of dialysis

Background. Peritoneal transport rate, a major determinant of peritoneal di alysis (PD) patient survival, increases in most patients starting on PD, wh ile in other patients peritoneal transport rate may decline. Although sever al factors may contribute to changes in peritoneal transport rate, inflamma tion is known to be associated with a high peritoneal transport rate, and r esidual renal function (RRF), which often declines after start of PD, may a lso be related to inflammation. Therefore, we hypothesized that changes in peritoneal transport rate during patients' first year on PD and declining R RF may be linked with inflammation. Methods. A total of 76 PD patients (40 males. mean age 56.8 +/- 14.1 years) , who underwent two peritoneal equilibration tests at a mean of 0.4 months and 1 year after beginning PD. were included in the study. Based on the cha nge in dialysate to plasma creatinine concentration ratio at 4-h dwell (D/P Cr) during first year on PD. the patients were divided into decreased or u nchanged (group DUC; n = 22) and increased (group 1, n = 54) groups. Results. Initially, group I had a lower proportion of high transporters and more often high serum C-reactive protein (sCRP, greater than or equal to 1 0 mg/l) and lower RRF compared with the DUC group. In group 1, serum albumi n and RRF decreased significantly and dialysate protein loss and glucose ab sorption increased significantly during the first year on PD. When patients were divided into two groups based on median change in RRF (1.9 ml/min), p atients with a decrease in RRF > 1.9 ml min during first year on PD had a h igher proportion of high sCRP, higher DP Cr, and higher changes in D/P Cr c ompared to patients with a decrease in RRF less than or equal to 1.9 ml/min . Patients with elevated sCRP at one year included a higher proportion of p atients who had high sCRP at the start of PD, higher increase in DT Cr, low er serum albumin. lower RRF, and more decrease in RRF during first year on PD compared with patients having normal sCRP. RRF was inversely correlated with changes in D/P Cr during the first year on PD (r = -0.28. P = 0.02). M ultiple regression analysis revealed that the only factors affecting change s in D/P Cr were high sCRP and a low RRF. Conclusions. Our preliminary short-term study suggests that changes in peri toneal transport rate during patients' first year on PD may be linked with inflammation and declining residual renal function. Inflammation and residu al renal function were identified as the only independent factors determini ng peritoneal transport rate during the first year on PD. It is possible th at inflammation may cause both an increase in peritoneal transport rate and a decline in residual renal function, or that the decline in residual rena l function and the increase in peritoneal transport rate may induce or aggr avate inflammation. Further studies are needed to confirm these findings.