Urine color expressed in CIE L*a*b* colorspace during rapid changes in hydration status

Area of Science:

• Physiology
• Biomedical Engineering
• Color Science

Background:

• Assessing hydration status is crucial for health and performance.
• Traditional hydration markers like urine osmolality and specific gravity may lack sensitivity to rapid fluid shifts.
• Objective measurement of urine color offers a potential alternative for monitoring hydration.

Purpose of the Study:

• To investigate the impact of rapid hydration changes on urine color.
• To compare the responsiveness of CIE L*a*b* color values to traditional hydration markers during rapid dehydration and rehydration.

Main Methods:

• A two-day crossover study involving 30 participants.
• Participants underwent rapid dehydration (2% body weight loss) or rapid rehydration (1000 mL water intake).
• Urine samples were analyzed for osmolality, specific gravity, subjective color, and objective color in CIE L*a*b* colorspace.

Main Results:

• Rapid dehydration led to significant changes in CIE L* (decrease) and b* (increase) values, alongside increased subjective color intensity.
• Rapid rehydration resulted in significant increases in CIE L* (increase) and a* (increase) values, and a decrease in b* (decrease) values.
• Traditional markers (osmolality, specific gravity) showed non-significant changes during acute dehydration.

Conclusions:

• CIE L*a*b* color values of urine are more responsive to rapid hydration changes than traditional markers.
• Objective urine color measurement may serve as a superior indicator of hydration status during acute fluid shifts.
• This study highlights the potential of using objective urine color analysis for hydration monitoring.