title: Relationship between urea clearance and ionic dialysance determined using a single-step conductivity profile.
abstract: BACKGROUND
  On-line determination of ionic dialysance (ID) has been used to measure the clearance of small solutes like urea. However, attempts to determine the in vivo relationship between ID and urea clearance have led to discordant findings. The aim of this study was to determine the relationship between the mean values of repeated instantaneous determinations of ID throughout a dialysis session ((m)ID), obtained using a single-step inlet dialysate conductivity profile, and the mean values of urea clearance corrected for access recirculation (K(eu1)), total recirculation (access plus cardiopulmonary recirculation, K(eu2)), and the entire postdialysis urea rebound (K(wb)).
  
  
  METHODS
  Eighty-two anuric patients on chronic thrice-weekly hemodialysis were studied using an Integra machine equipped with the Diascan module for the automatic determination of ID. The mean values of repeated ID measurements made at 30-minute intervals were compared with K(eu1) (available for only 31 patients), K(eu2), and K(wb).
  
  
  RESULTS
  The results in all 82 patients were: (m)ID = 176 +/- 23 mL/min; K(eu2) = 181 +/- 25 mL/min; K(wb) = 159 +/- 22 mL/min. The mean (m)ID/K(wb) and (m)ID/K(eu2) ratios were, respectively, 1.11 +/- 0.06 and 0.98 +/- 0.06. The results in the 31 patients for whom K(eu1) values were available were: (m)ID = 179 +/- 24 mL/min and K(eu1) = 200 +/- 27 mL/min; the mean (m)ID/K(eu1) ratio was 0.90 +/- 0.05.
  
  
  CONCLUSIONS
  The mean value of repeated ID determinations obtained using a single-step conductivity profile underestimates urea clearance corrected for access recirculation, and may be considered an adequate estimate of urea clearance corrected for total recirculation.
authors.affiliation: Department of Nephrology and Dialysis, A. Manzoni Hospital, Lecco, Italy. nefrologia@ospedale.lecco.it
authors.forename: Salvatore
authors.initials: S
authors.lastname: Di Filippo
authors.forename: Pietro
authors.initials: P
authors.lastname: Pozzoni
authors.forename: Celestina
authors.initials: C
authors.lastname: Manzoni
authors.forename: Simeone
authors.initials: S
authors.lastname: Andrulli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pontoriero
authors.forename: Francesco
authors.initials: F
authors.lastname: Locatelli
mesh_terms: D001002:Anuria / Q000378:metabolism / Q000628:therapy; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy*; D007700:Kinetics; D008954:Models, Biological; D012044:Regression Analysis; D006435:Renal Dialysis / Q000295:instrumentation / Q000379:methods*; D014508:Urea / Q000378:metabolism*
chemical_list: D014508:Urea