title: Reduction in protein-bound solutes unacceptable as marker of dialysis efficacy during alternate-night nocturnal hemodialysis.
abstract: BACKGROUND
  The uremic retention solutes indoxyl sulfate and p-cresyl sulfate are linked to cardiovascular disease and overall survival. Dialytic clearances are limited, which is principally attributed to tight protein binding. Extending dialysis duration would be expected to substantially increase protein-bound uremic solute removal. The aim of the current study was to study protein-bound uremic retention solute clearances and kinetics during longer-hours nocturnal hemodialysis.
  
  
  METHODS
  In a prospective cohort study of 32 maintenance alternate-night nocturnal hemodialysis patients, we followed serum concentrations, solute removals and solute clearances of p-cresyl sulfate and indoxyl sulfate. Spent dialysate sampling was fractionated to compare solute removals between the first 4 h and next 4 h of nocturnal dialysis. Single-compartment variable volume kinetics were calculated.
  
  
  RESULTS
  Dialytic clearances of protein-bound uremic retention solutes are maintained during nocturnal (longer-hours) dialysis. Clearances of indoxyl sulfate exceed those of p-cresyl sulfate, presumably due to less tight protein-binding. Apparent distribution volumes increase substantially during nocturnal dialysis, indicative of multi-compartmental behavior of the protein-bound uremic retention solutes indoxyl sulfate and p-cresyl sulfate.
  
  
  CONCLUSIONS
  During nocturnal hemodialysis, serum concentrations of protein-bound solute concentrations are reduced less than predicted. Reduction ratios are not a valid tool to estimate total solute removal of protein-bound uremic retention solutes.
authors.affiliation: Division of Nephrology, Department of Medicine, University Hospital Leuven, Belgium.
authors.forename: Bjorn
authors.initials: B
authors.lastname: Meijers
authors.forename: Nigel D
authors.initials: ND
authors.lastname: Toussaint
authors.forename: Timothy
authors.initials: T
authors.lastname: Meyer
authors.forename: Bert
authors.initials: B
authors.lastname: Bammens
authors.forename: Kristin
authors.initials: K
authors.lastname: Verbeke
authors.forename: Yves
authors.initials: Y
authors.lastname: Vanrenterghem
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kerr
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
mesh_terms: D003408:Cresols / Q000032:analysis / Q000378:metabolism*; D005260:Female; D015312:Hemodialysis Solutions / Q000737:chemistry; D006801:Humans; D007200:Indican / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011485:Protein Binding; D006435:Renal Dialysis / Q000379:methods / Q000592:standards*; D013463:Sulfuric Acid Esters; D013997:Time Factors
chemical_list: D003408:Cresols; D015312:Hemodialysis Solutions; D013463:Sulfuric Acid Esters; C408690:4-cresol sulfate; D007200:Indican