title: Time profiles of peritoneal and renal clearances of different uremic solutes in incident peritoneal dialysis patients.
abstract: BACKGROUND
  Residual renal function (RRF) contributes substantially to the adequacy of peritoneal dialysis (PD). In the presence of RRF, maintenance of an adequate fluid balance is facilitated, level of systemic inflammation is lower, and renal endocrine functions are preserved. The beneficial impact of RRF also may be related to the preservation of specific renal elimination mechanisms, such as tubular metabolism or secretion, which are crucial for the removal of some uremic retention solutes.
  
  
  METHODS
  Time profiles of peritoneal and renal clearances of urea nitrogen (60 d), creatinine (113 d), phosphate (96 d), the middle molecule beta2-microglobulin (beta2M; 11.8 kd), and the protein-bound solute p-cresol (108 d) were investigated prospectively in 24 incident PD patients. Data were analyzed by using the linear mixed models procedure.
  
  
  RESULTS
  During a median follow-up of 7.2 months (range, 5.6 to 8.6 months), RRF (P = 0.001) and 24-hour urine volume (P = 0.004) declined significantly. Twenty-four-hour peritoneal drainage volume increased (P < 0.0001). Renal clearances of urea nitrogen (P = 0.0002), creatinine (P = 0.001), and phosphate (P = 0.001) decreased. Peritoneal clearances of these solutes increased (P = 0.002, P < 0.0001, and P < 0.0001, respectively). There was a decline in renal clearances of beta2M (P = 0.0004) and p-cresol (P < 0.0001). No change in peritoneal clearances of these solutes was noted (P = 0.188 and P = 0.559, respectively).
  
  
  CONCLUSIONS
  Increasing PD dose may compensate for deteriorating RRF with respect to the elimination of water-soluble solutes. This is not the case for the middle molecule beta2M and the protein-bound solute p-cresol.
authors.affiliation: Division of Nephrology, Department of Medicine, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Bert
authors.initials: B
authors.lastname: Bammens
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
authors.forename: Kristin
authors.initials: K
authors.lastname: Verbeke
authors.forename: Yves
authors.initials: Y
authors.lastname: Vanrenterghem
mesh_terms: D000328:Adult; D000368:Aged; D001202:Ascitic Fluid / Q000378:metabolism*; D015897:Comorbidity; D003404:Creatinine / Q000378:metabolism; D003408:Cresols / Q000493:pharmacokinetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008970:Molecular Weight; D009584:Nitrogen / Q000378:metabolism; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000706:statistics & numerical data*; D010710:Phosphates / Q000378:metabolism; D011446:Prospective Studies; D011485:Protein Binding; D012995:Solubility; D013997:Time Factors; D014118:Toxins, Biological / Q000378:metabolism; D014508:Urea / Q000378:metabolism; D014511:Uremia / Q000097:blood*; D001613:beta 2-Microglobulin / Q000378:metabolism
chemical_list: D003408:Cresols; D010710:Phosphates; D014118:Toxins, Biological; D001613:beta 2-Microglobulin; C026865:uremia middle molecule toxins; C032538:4-cresol; D014508:Urea; D003404:Creatinine; D009584:Nitrogen