title: Acid-base disorders associated with serum electrolyte patterns in patients on hemodiafiltration.
abstract: BACKGROUND
  Metabolic acidosis (MAC) is a common aspect of dialysis-dependent patients. It is definitely caused by acid retention; however, the influence of other plasma ions is unclear. Understanding the mechanism of MAC and its correction is important when choosing the dialysis solution. Therefore, we assessed the relationship between intradialytic change of acid-base status and serum electrolytes.
  
  
  METHODS
  We studied 68 patients on post-dilution hemodiafiltration, using dialysate bicarbonate concentration 32mmol/L. The acid-base disorders were evaluated by the traditional Siggaard-Anderson and modern Stewart approaches.
  
  
  RESULTS
  The mean pre-dialysis pH was 7.38, standard base excess (SBE) -1.5, undetermined anions (UA(-)) 7.5, sodium-chloride difference (Diff(NaCl)) 36.2mmol/L. MAC was present in 34% of patients, of which 83% had an increased UA(-) as a major cause of MAC. The mean nPCR was 0.99g/kg/day and correlated negatively with SBE. After dialysis, metabolic alkalosis predominated in 81%. The mean post-dialysis pH was 7.45, SBE 4, UA(-) 2.6, Diff(NaCl) 36.9mmol/L. ΔSBE significantly correlated with ΔUA(-), but not with ΔDiff(NaCl) or ΔCl(-).
  
  
  CONCLUSIONS
  MAC in patients on hemodiafiltration is mainly caused by acid retention and is associated with higher protein intake. We did not prove the effect of sodium or chloride on acid-base balance. Even though we used a relatively low concentration of dialysate bicarbonate, we recorded a high proportion of post-dialysis alkalosis caused by the excessive decrease of undetermined anions, which had been completely replaced by bicarbonate and indicated the elimination of undesirable anions, as well as of normal endogenous anions.
authors.affiliation: Department of medicine, 2nd Medical Faculty of Charles University and Faculty hospital Motol, V Úvalu 84, 150 06, Prague 5, Czech Republic; B. Braun Avitum Praha Nusle Dialysis Center, Táborská 325/57, 140 00, Prague 4, Czech Republic. Electronic address: havlin.jan@gmail.com.
authors.forename: Jan
authors.initials: J
authors.lastname: Havlin
authors.affiliation: Department of medicine, 2nd Medical Faculty of Charles University and Faculty hospital Motol, V Úvalu 84, 150 06, Prague 5, Czech Republic.
authors.forename: Otto
authors.initials: O
authors.lastname: Schück
authors.affiliation: Department of medicine, 2nd Medical Faculty of Charles University and Faculty hospital Motol, V Úvalu 84, 150 06, Prague 5, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Charvat
authors.affiliation: Department of rehabilitation and sports medicine, 2nd Medical Faculty of Charles University and Faculty hospital Motol, Prague, Czech Republic.
authors.forename: Krystof
authors.initials: K
authors.lastname: Slaby
authors.affiliation: Department of medicine, 2nd Medical Faculty of Charles University and Faculty hospital Motol, V Úvalu 84, 150 06, Prague 5, Czech Republic.
authors.forename: Miroslava
authors.initials: M
authors.lastname: Horackova
authors.affiliation: Department of medicine I, Charles University Medical school and teaching hospital, Pilsen, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Klaboch
authors.affiliation: Fresenius medical care DS, Dialysis centre Motol, Prague, Czech Republic.
authors.forename: Michaela
authors.initials: M
authors.lastname: Sagova
authors.affiliation: B. Braun Avitum Praha Nusle Dialysis Center, Táborská 325/57, 140 00, Prague 4, Czech Republic.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Vankova
authors.affiliation: Department of medicine, 2nd Medical Faculty of Charles University and Faculty hospital Motol, V Úvalu 84, 150 06, Prague 5, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Matousovic
mesh_terms: D000137:Acid-Base Imbalance / Q000209:etiology*; D000368:Aged; D004573:Electrolytes / Q000097:blood*; D005260:Female; D017583:Hemodiafiltration / Q000009:adverse effects*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000628:therapy*; D008297:Male; D008875:Middle Aged
chemical_list: D004573:Electrolytes
keywords: Acid-base; Base excess; Electrolyte; Hemodiafiltration; Sodium-chloride difference; Stewart