P1155REMOVAL OF PHOSPHATE AND CREATININE DURING PD WITH DIFFERENT GLUCOSE CONCENTRATIONS

Abstract

Abstract Background and Aims Adequate removal of creatinine and phosphate is one of the key objectives in peritoneal dialysis (PD). Whereas the mechanism of creatinine removal is well known, there are gaps in understanding regulation of phosphate removal. Clinical studies show that although the size of both molecules is similar, their removal might behave differently (Badve et al CJASN 2008). Several, but not all, studies have suggested that peritoneal phosphate clearance is larger when using CAPD than APD prescriptions, suggesting the dwell time or duration is an important determinant of phosphate clearance. The aim of the study was to investigate specifically the effect of dwell duration at the level of single PD exchange with different glucose concentrations on peritoneal phosphate clearance. Method A prolonged 8-hour PET was carried out in 32 clinically stable PD patients with each of three glucose-based solutions: 1.36% (G1), 2.27% (G2), and 3.86% (G3) with temporary drainage at 1 and 4 hours of peritoneal dwell. Dialysate and blood samples were taken to measure infused and drained volume and concentration of phosphate and creatinine in dialysate and blood. Clearances were calculated for a single exchange for each solution and for 4-hour (4H) and 8-hour (8H) dwell periods. For each patient, the 4-hour creatinine D/P ratio for G3 was calculated. The clearance ratio, ClR, defined as the ratio of solute clearance for particular solution to its clearance for the G1 solution, was calculated for both solutes and each solution and dwell durations. Results The obtained values of 4H creatinine D/P ratio for G3 solution were 0.67±0.11 (mean±SD). The values of solute clearances per single exchange expressed in mL/min, are presented in table below. Creatinine and phosphate clearances were found to be solution and dwell duration dependent with p<0.001. The clearances of both solutes were correlated for the same dwell duration or solution (not for creatinine G2 for 4H vs 8H) with p<0.05. Moreover, solute clearances were also correlated with creatinine D/P for 4H but not for 8H. The clearances of phosphate were also correlated with that for creatinine each solution at both dwell durations with p<0.001. Both calculated ClR were found to be dependent on the solution (p<0.001) but not dwell duration. Similar dependence on solution and correlations are valid in one analyze solute mass removal. Conclusion Phosphate and creatinine clearances were found to be well correlated during a long, 8-hour PET proving similarities in their transport. Interestingly, the dependence of both clearances and ClR on solution glucose concentration suggest that the removal of phosphate as well as creatinine depends on the ultrafiltration induced by glucose concentration in dialysis solution.