European Journal of Applied Physiology

, Volume 114, Issue 1, pp 85–92

Assessment of extracellular dehydration using saliva osmolality

  • Brett R. Ely
  • Samuel N. Cheuvront
  • Robert W. Kenefick
  • Marissa G. Spitz
  • Kristen R. Heavens
  • Neil P. Walsh
  • Michael N. Sawka
Original Article

Abstract

Introduction

When substantial solute losses accompany body water an isotonic hypovolemia (extracellular dehydration) results. The potential for using blood or urine to assess extracellular dehydration is generally poor, but saliva is not a simple ultra-filtrate of plasma and the autonomic regulation of salivary gland function suggests the possibility that saliva osmolality (Sosm) may afford detection of extracellular dehydration via the influence of volume-mediated factors.

Purpose

This study aimed to evaluate the assessment of extracellular dehydration using Sosm. In addition, two common saliva collection methods and their effects on Sosm were compared.

Methods

Blood, urine, and saliva samples were collected in 24 healthy volunteers during paired euhydration and dehydration trials. Furosemide administration and 12 h fluid restriction were used to produce extracellular dehydration. Expectoration and salivette collection methods were compared in a separate group of eight euhydrated volunteers. All comparisons were made using paired t-tests. The diagnostic potential of body fluids was additionally evaluated.

Results

Dehydration (3.1 ± 0.5 % loss of body mass) decreased PV (−0.49 ± 0.12 L; −15.12 ± 3.94 % change), but Sosm changes were marginal (<10 mmol/kg) and weakly correlated with changes in absolute or relative PV losses. Overall diagnostic accuracy was poor (AUC = 0.77–0.78) for all body fluids evaluated. Strong agreement was observed between Sosm methods (Expectoration: 61 ± 10 mmol/kg, Salivette: 61 ± 8 mmol/kg, p > 0.05).

Conclusions

Extracelluar dehydration was not detectable using plasma, urine, or saliva measures. Salivette and expectoration sampling methods produced similar, consistent results for Sosm, suggesting no methodological influence on Sosm.

Keywords

Hypohydration Hypovolemia Volume depletion Hydration assessment Furosemide 

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Copyright information

© Springer-Verlag Berlin Heidelberg (outside the USA) 2013

Authors and Affiliations

  • Brett R. Ely
    • 1
    • 2
  • Samuel N. Cheuvront
    • 1
  • Robert W. Kenefick
    • 1
  • Marissa G. Spitz
    • 1
  • Kristen R. Heavens
    • 1
  • Neil P. Walsh
    • 3
  • Michael N. Sawka
    • 4
  1. 1.Thermal and Mountain Medicine DivisionU.S. Army Research Institute of Environmental MedicineNatickUSA
  2. 2.Department of Human PhysiologyUniversity of OregonEugeneUSA
  3. 3.Extremes Research GroupBangor UniversityBangorUK
  4. 4.School of Applied Physiology, Georgia Institute of TechnologyAtlantaUSA

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