title: An aggregate urine analysis tool to detect acute dehydration.
abstract: OBJECTIVE
  Urine sampling has previously been evaluated for detecting dehydration in young male athletes. The present study investigated whether urine analysis can serve as a measure of dehydration in men and women of a wide age span.
  
  
  METHODS
  Urine sampling and body weight measurement were undertaken before and after recreational physical exercise (median time: 90 min) in 57 volunteers age 17-69 years (mean age: 42). Urine analysis included urine color, osmolality, specific gravity, and creatinine.
  
  
  RESULTS
  The volunteers' body weight decreased 1.1% (mean) while they exercised. There were strong correlations between all 4 urinary markers of dehydration (r = .73-.84, p < .001). Researchers constructed a composite dehydration index graded from 1 to 6 based on these markers. This index changed from 2.70 before exercising to 3.55 after exercising, which corresponded to dehydration of 1.0% as given by a preliminary reference curve based on seven previous studies in athletes. Men were slightly dehydrated at baseline (mean: 1.9%) compared with women (mean: 0.7%; p < .001), though age had no influence on the results. A final reference curve that considered both the present results and the 7 previous studies was constructed in which exercise-induced weight loss (x) was predicted by the exponential equation x = 0.20 dehydration index1.86.
  
  
  CONCLUSIONS
  Urine sampling can be used to estimate weight loss due to dehydration in adults up to age 70. A robust dehydration index based on four indicators reduces the influence of confounders.
authors.affiliation: Dept. of Anesthesiology, Linköping University, Linköping, Sweden.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Hahn
authors.forename: Nana
authors.initials: N
authors.lastname: Waldréus
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D015992:Body Mass Index; D001835:Body Weight; D003681:Dehydration / Q000175:diagnosis* / Q000652:urine*; D015444:Exercise; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016482:Urinalysis / Q000379:methods*; D015431:Weight Loss / Q000502:physiology; D055815:Young Adult
chemical_list: D015415:Biomarkers