Association of Plasma Uremic Solute Levels with Residual Kidney Function in Children on Peritoneal Dialysis

Background and objectives. Residual native kidney function confers health benefits in dialysis patients. It can facilitate control of extracellular volume and inorganic ion concentrations. Residual kidney function can also limit the accumulation of uremic solutes. This study assessed whether lower plasma concentrations of uremic solutes were associated with residual kidney function in pediatric patients on peritoneal dialysis. Design, setting, participants, and measurements. Samples were analyzed from 29 pediatric peritoneal dialysis patients including 13 without residual kidney function and 10 with residual kidney function. Metabolomic analysis by untargeted mass spectrometry compared plasma solute levels in patients with and without residual kidney function. Dialytic and residual clearances of selected solutes were also measured by assays employing chemical standards. Results. Metabolomic analysis showed that plasma levels of 256 uremic solutes in patients with residual kidney function averaged 64 (51-81 IQR) percent of the values in patients without residual kidney function who had similar total Kt/Vurea. The plasma levels were significantly lower for 59 of the 256 solutes in the patients with residual kidney function and significantly higher for none. Assays employing chemical standards showed that residual kidney function provides a higher portion of the total clearance for non-urea solutes than it does for urea. Conclusions. Concentrations of many uremic solutes are lower in peritoneal dialysis patients with residual kidney function than in those without residual kidney function receiving similar treatment as assessed by Kt/Vurea.