title: Use of salivary osmolality to assess dehydration.
abstract: OBJECTIVE
  To investigate the ability of salivary osmolality to assess dehydration while subjects perform alternating work/rest cycles in personal protective equipment (PPE).
  
  
  METHODS
  Eight healthy men (mean ± standard deviation age: 23.5 ± 4.9 years; body fat: 17.8% ± 5.0%; maximum volume of oxygen consumption [VO(2max)]: 57.2 ± 5.5 mL·kg(-1)·min(-1)) performed two exercise trials: one while wearing shorts and a T-shirt (EX) and one while wearing firefighting PPE (EX+PPE). Saliva samples were taken before exercise, at minutes 40, 80, and 120 of the exercise trial, and during recovery.
  
  
  RESULTS
  Percent body mass loss (BML) was significantly greater while the subjects were wearing PPE (2.18% ± 0.54% vs. control 0.81% ± 0.30%). Salivary osmolality increased significantly in both trials (73.4 ± 12.4 to 125.1 ± 30.3 mOsm·kg(-1) and 70.1 ± 12.5 to 83.6 ± 17.7 mOsm·kg(-1)); however, the increase in the EX+PPE trial was significantly greater than the increase in the EX trial. Plasma osmolality did not change significantly in either trial, whereas urinary osmolality increased significantly in both trials. Changes in salivary osmolality were strongly correlated with percent BML (r = 0.80; p < 0.01).
  
  
  CONCLUSIONS
  Salivary osmolality may be a sensitive indicator of moderate dehydration under carefully controlled conditions.
authors.affiliation: Department of Health & Exercise Sciences, Skidmore College, Saratoga Springs, New York 12866, USA. dsmith@skidmore.edu
authors.forename: Denise L
authors.initials: DL
authors.lastname: Smith
authors.forename: Inga
authors.initials: I
authors.lastname: Shalmiyeva
authors.forename: Jacob
authors.initials: J
authors.lastname: Deblois
authors.forename: Molly
authors.initials: M
authors.lastname: Winke
mesh_terms: D000704:Analysis of Variance; D001831:Body Temperature; D003681:Dehydration / Q000175:diagnosis* / Q000209:etiology; D015444:Exercise; D006339:Heart Rate; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D011481:Protective Clothing; D018570:Risk Assessment; D012463:Saliva / Q000737:chemistry*; D014882:Water-Electrolyte Balance; D015431:Weight Loss; D055815:Young Adult