title: Low sodium haemodialysis reduces interdialytic fluid consumption but paradoxically increases post-dialysis thirst.
abstract: BACKGROUND
  Interdialytic weight gain (IDWG) can be reduced by lowering the dialysate sodium concentration ([Na]) in haemodialysis patients. It has been assumed that this is because thirst is reduced, although this has been difficult to prove. We compared thirst patterns in stable haemodialysis patients with high and low IDWG using a novel technique and compared the effect of low sodium dialysis (LSD) with normal sodium dialysis (NSD).
  
  
  METHODS
  Eight patients with initial high IDWG and seven with low IDWG completed hourly visual analogue ratings of thirst using a modified palmtop computer during the dialysis day and the interdialytic day. The dialysate [Na] was progressively reduced by up to 5 mmol/l over five treatments. Dialysis continued at the lowest attained [Na] for 2 weeks and the measurements were repeated. The dialysate [Na] then returned to baseline and the process was repeated.
  
  
  RESULTS
  Baseline interdialytic day mean thirst was higher than the dialysis day mean for the high IDWG group (49.9+/-14.0 vs 36.2+/-16.6) and higher than the low weight gain group (49.9+/-14.0 vs 34.1+/-14.6). This trend persisted on LSD, but there was a pronounced increase in post-dialysis thirst scores for both groups (high IDWG: 46+/-13 vs 30+/-21; low IDWG: 48+/-24 vs 33+/-18). The high IDWG group demonstrated lower IDWG during LSD than NSD (2.23+/-0.98 vs 2.86+/-0.38 kg; P<0.05).
  
  
  CONCLUSIONS
  Our results indicate that patients with high IDWG experience more intense feelings of thirst on the interdialytic day. LSD reduces their IDWG, but paradoxically increases thirst in the immediate post-dialysis period.
authors.affiliation: Leeds University School of Medicine, Leeds, UK.
authors.forename: Alister
authors.initials: A
authors.lastname: Oliver
authors.forename: Mark
authors.initials: M
authors.lastname: Wright
authors.forename: Andrew
authors.initials: A
authors.lastname: Matson
authors.forename: Graham
authors.initials: G
authors.lastname: Woodrow
authors.forename: Neil
authors.initials: N
authors.lastname: King
authors.forename: Louise
authors.initials: L
authors.lastname: Dye
mesh_terms: D004326:Drinking; D015312:Hemodialysis Solutions / Q000737:chemistry*; D006801:Humans; D009994:Osmolar Concentration; D006435:Renal Dialysis; D012964:Sodium / Q000008:administration & dosage / Q000494:pharmacology*; D013894:Thirst; D015430:Weight Gain / Q000502:physiology
chemical_list: D015312:Hemodialysis Solutions; D012964:Sodium