title: Effect of increased water intake on plasma copeptin in patients with chronic kidney disease: results from a pilot randomised controlled trial.
abstract: OBJECTIVE
  Increased water intake may have a beneficial effect on the kidney through suppression of plasma vasopressin. We examined the effect of increased water intake on plasma copeptin (a marker of vasopressin) over 6 weeks in patients with chronic kidney disease.
  
  
  METHODS
  Secondary analysis of a randomised controlled parallel-group pilot trial.
  
  
  METHODS
  Canada, 2012-2013.
  
  
  METHODS
  28 patients with stage 3 chronic kidney disease randomised (2:1) to a hydration (n=17) or control group (n=11).
  
  
  METHODS
  The hydration group was coached to increase water intake by up to 1.5 L/day for 6 weeks. The control group was asked to maintain regular water intake.
  
  
  METHODS
  Participants provided blood and 24 h urine samples at baseline and 6 weeks. Change in plasma copeptin was compared within and between study groups.
  
  
  RESULTS
  Participants were 64% male with a mean age of 62 years and an estimated glomerular filtration rate of 40 mL/min/1.73 m(2). Between baseline and 6 weeks, 24 h urine volume increased by 0.7 L/day in the hydration group, rising from 2.3 to 3.0 L/day (p=0.01), while decreasing by 0.3 L/day among controls, from 2.0 to 1.7 L/day (p=0.07); between-group difference: 0.9 L/day (95% CI 0.37 to 1.46; p=0.002). In the hydration group, median copeptin decreased by 3.6 pmol/L, from 15.0 to 10.8 pmol/L (p=0.005), while remaining stable among controls at 19 pmol/L (p=0.76; p=0.19 for the between-group difference in median change); the between-group difference in mean change was 5.4 pmol/L (95% CI -1.2 to 12.0; p=0.11).
  
  
  CONCLUSIONS
  Adults with stage 3 chronic kidney disease can be successfully randomised to drink approximately 1 L more per day than controls. This increased water intake caused a significant decrease in plasma copeptin concentration. Our larger 12-month trial will examine whether increased water intake can slow renal decline in patients with chronic kidney disease.
  
  
  BACKGROUND
  NCT01753466.
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Sontrop
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Shi-Han
authors.initials: SH
authors.lastname: Huang
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.
authors.forename: Louise
authors.initials: L
authors.lastname: Moist
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: House
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Kerri
authors.initials: K
authors.lastname: Gallo
authors.affiliation: Division of Nephrology, Department of Medicine, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: William F
authors.initials: WF
authors.lastname: Clark
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002170:Canada; D004326:Drinking; D005260:Female; D005919:Glomerular Filtration Rate; D006020:Glycopeptides / Q000097:blood*; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D051436:Renal Insufficiency, Chronic / Q000097:blood*
chemical_list: D015415:Biomarkers; D006020:Glycopeptides; C048197:copeptins
keywords: 24-hour urine volume; chronic kidney disease; coeptin; glomerular filtration rate; water intake