title: Effects of drinking water quality on urinary parameters in men with and without urinary tract stones.
abstract: OBJECTIVE
  There is some controversy regarding the impact of water hardness on stone risk. Our study addresses this issue in a controlled setting.
  
  
  METHODS
  Fifteen stone-former (SF) and 14 non-stone-former (NSF) males participated in this study in 3 intervals of 2 days each. Subjects collected a 24-hour urine sample while consuming a self-selected diet. They were then administered controlled diets. During the first 2 days, patients consumed water of minimal hardness (WMH), followed by tap water (TW) with moderate hardness on days 3 and 4, and mineral water (MW) on the final 2 days. Calcium (Ca), phosphorus, uric acid, oxalate, citrate, magnesium (Mg), sodium, potassium, and creatinine (Cr) content were measured in 24-hour urine samples on days 2, 4, and 6.
  
  
  RESULTS
  Differences in water hardness and analytes were statistically significant among the different water types (P < .05). Urinary output in both groups increased during intervention with all 3 varieties of water (P < .05). Specific gravity of urine decreased in both groups drinking WMH and TW (P < .05) but not with MW. Mg/g Cr level was higher in NSF at baseline (P < .01), WMH (P < .05), and TW (P < .05). With the increase in drinking water hardness, Ca/g Cr ratio increased in SF but not in NSF (P < .05).
  
  
  CONCLUSIONS
  NSF had significantly higher urinary Mg/g Cr excretion rate before intervention than SF (P < .01). Increasing drinking water hardness while controlling for all other factors increased Ca/g Cr ratio in SF, rendering them at least theoretically more inclined to stone formation.
authors.affiliation: Wake Forest University Baptist Medical Center, Department of Urology, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
authors.forename: Majid
authors.initials: M
authors.lastname: Mirzazadeh
authors.forename: Mina Ghadimi
authors.initials: MG
authors.lastname: Nouran
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Richards
authors.forename: Mariam
authors.initials: M
authors.lastname: Zare
mesh_terms: D000293:Adolescent; D000328:Adult; D003404:Creatinine / Q000652:urine; D060766:Drinking Water / Q000737:chemistry / Q000592:standards*; D006244:Hardness; D006801:Humans; D008274:Magnesium / Q000652:urine; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000652:urine; D011446:Prospective Studies; D012964:Sodium / Q000652:urine; D013046:Specific Gravity; D014545:Urinary Calculi / Q000652:urine*; D014556:Urine / Q000737:chemistry*; D060753:Water Quality; D055815:Young Adult
chemical_list: D060766:Drinking Water; D012964:Sodium; D003404:Creatinine; D008274:Magnesium; D011188:Potassium