Assessing hydration status: the elusive gold standard
1Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269-1110, USA. lawrence.armstrong@uconn.edu
Journal of the American College of Nutrition
|October 27, 2007
Summary
Assessing total body water (TBW) hydration is complex. Current methods, including plasma osmolality, may not accurately reflect daily fluid changes, necessitating new real-time techniques.
Area of Science:
- Physiology
- Sports Medicine
- Nutrition Science
Background:
- Total body water (TBW) dynamics are intricate and challenging to measure accurately.
- Existing hydration assessment techniques vary in validity across different situations.
Purpose of the Study:
- To review and evaluate 13 hydration assessment techniques for measuring total body water (TBW).
- To identify limitations of current methods, particularly plasma osmolality (P(osm)), in reflecting daily hydration fluctuations.
- To guide future research towards developing superior hydration assessment tools.
Main Methods:
- Systematic review of 13 hydration assessment techniques.
- Evaluation of existing validated laboratory methods for TBW and extracellular volume.
- Analysis of evidence regarding concentration measurements like plasma osmolality (P(osm)) for assessing TBW changes.
Main Results:
- Validated laboratory methods exist for measuring total body water (TBW) and extracellular volume.
- No current concentration measurement, including plasma osmolality (P(osm)), is proven to accurately represent TBW gain/loss during daily activities.
- A single blood or urine sample is insufficient to represent dynamic TBW and fluid compartment fluctuations.
Conclusions:
- Current hydration assessment methods, including plasma osmolality, have limitations in reflecting real-time total body water (TBW) changes during daily life.
- Future research must focus on developing precise, accurate, reliable, non-invasive, portable, and simple real-time hydration assessment techniques.
- Further investigation is needed to clarify the relationship between plasma osmolality (P(osm)) and TBW oscillations in diverse physiological scenarios.
