title: Water prescription in autosomal dominant polycystic kidney disease: a pilot study.
abstract: OBJECTIVE
  In animal models of polycystic kidney disease, the ingestion of large amounts of water promotes diuresis by suppressing plasma levels of arginine vasopressin (AVP) and renal levels of cAMP, slowing cyst progression. Whether simple water ingestion is a potential therapeutic strategy for individuals with autosomal dominant polycystic kidney disease (ADPKD) is unknown. In this study, a simple method to quantify the amount of water to achieve a specific mean urine osmolality target in patients with ADPKD was developed and tested.
  
  
  METHODS
  In eight ADPKD patients eating typical diets, osmolality and volume were measured in 24-hour urine collections. The amount of additional ingested water required daily to achieve a mean urine osmolality of 285 ± 45 mosm/kg was determined. Participants were instructed to distribute the prescribed water over waking hours for each of 5 days. Blood chemistries, 24-hour urine collections, BP, and weight were measured before and after the period of supplemental water intake.
  
  
  RESULTS
  Five patients achieved the 285 mosm/kg urine target without difficulty. Mean urine osmolality decreased and mean urine volume increased; serum sodium, weight, and BP were unchanged. Daily osmolar excretion remained constant, indicating a stable ad lib dietary intake of solutes and protein over the 2-week study period.
  
  
  CONCLUSIONS
  The amount of additional water needed to achieve a urine osmolality target can be approximated from the urine osmolar excretion in ADPKD patients eating typical diets, providing a quantitative method to prescribe supplemental water for such individuals.
authors.affiliation: Division of Nephrology and Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, USA. cwang@kumc.edu
authors.forename: Connie J
authors.initials: CJ
authors.lastname: Wang
authors.forename: Catherine
authors.initials: C
authors.lastname: Creed
authors.forename: Franz T
authors.initials: FT
authors.lastname: Winklhofer
authors.forename: Jared J
authors.initials: JJ
authors.lastname: Grantham
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D010865:Pilot Projects; D016891:Polycystic Kidney, Autosomal Dominant / Q000652:urine*; D014867:Water / Q000008:administration & dosage*
chemical_list: D014867:Water