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Reference change values for monitoring dehydration
Samuel N Cheuvront1, Callum G Fraser, Robert W Kenefick
1U.S. Army Research Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Natick, MA 01760-5007, USA. Samuel.n.cheuvront@us.army.mil
Clinical Chemistry and Laboratory Medicine
|March 25, 2011
Summary
This study developed a tool to quantify dehydration probability using plasma osmolality, urine specific gravity, or body mass changes. The tool provides a simple, graphical method to assess dehydration likelihood, aiding clinical evaluation.
Area of Science:
- Physiology
- Biostatistics
- Medical Diagnostics
Background:
- Dehydration is a prevalent medical condition often requiring subjective assessment.
- Developing objective tools for dehydration probability is crucial for accurate diagnosis and management.
Purpose of the Study:
- To create a quantitative and graphical tool for assessing dehydration probability.
- To validate the tool's efficacy using volunteer dehydration studies.
Main Methods:
- Calculated reference change values (RCVs) for plasma osmolality (P(osm)), urine specific gravity (U(sg)), and body mass (B(m)) at various statistical probabilities.
- Developed an empirical equation and a graphical representation linking measured changes to dehydration probability using Z-scores.
Main Results:
- Volunteers experienced moderate dehydration (-2.1% to -3.5% B(m)).
- The tool yielded high median probabilities for dehydration: 0.98 for P(osm), 0.97 for U(sg), and 0.97 for B(m).
- These probabilities corresponded to 'very likely' to 'virtually certain' qualitative categories.
Conclusions:
- A straightforward quantitative and graphical tool for estimating dehydration probability has been developed.
- The tool aids in determining dehydration likelihood based on serial measurements of P(osm), U(sg), or B(m).
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