Received June 21, 2007
Accepted on October 8, 2007

ORIGINAL ARTICLES

Removal of the Protein-Bound Solutes Indican and P-Cresol Sulfate by Peritoneal Dialysis

Nhat M. Pham ^*, Natalie S. Recht ^*, Thomas H. Hostetter , and Timothy W. Meyer ^*1

*Department of Medicine, VA Palo Alto Health Care System, and Stanford University, Palo Alto, California; and Department of Medicine, Albert Einstein College of Medicine, New York, New York

¹ To whom correspondence should be addressed. E-mail: twmeyer{at}stanford.edu.

	Abstract

Background and objectives: Protein-bound solutes are poorly cleared by peritoneal dialysis. We examined the hypothesis that plasma concentrations of bound solutes would therefore rise as residual renal function is lost.

Design, setting, participants, & measurements: Clearances of urea indican and p-cresol sulfate were measured in peritoneal dialysis patients with and without residual function.

Results: In patients with residual function, protein binding restricted the peritoneal indican and p-cresol sulfate clearances to 0.3 ± 0.1 ml/min, as compared to the peritoneal urea clearance of 5.5 ± 1.1 ml/min. The urinary indican and p-cresol sulfate clearances of 2.7 ± 2.5 and 1.3 ± 1.0 ml/min were closer to the urinary urea clearance of 3.9 ± 2.2 ml/min, reflecting the superior ability of native kidney function to clear bound solutes. Urinary clearance thus provided the majority of the total indican and p-cresol sulfate clearances of 3.0 ± 2.5 and 1.6 ± 1.0 ml/min in patients with residual function but the minority of total urea clearance of 9.4 ± 2.2 ml/min. Loss of residual function lowered the total clearances for indican and p-cresol sulfate to 0.5 ± 0.2 and 0.4 ± 0.2 ml/min, whereas the urea clearance fell only slightly. However there was only a modest increase in the plasma indican level and no increase in the plasma p-cresol sulfate level in patients with no residual function because reduction in the daily removal of these solutes accompanied the reduction in their total clearance rates.

Conclusions: Reduction in the removal of indican and p-cresol sulfate kept plasma levels from rising markedly when residual function was lost.