Accuracy of Urine Color to Detect Equal to or Greater Than 2% Body Mass Loss in Men

J Athl Train. 2015 Dec;50(12):1306-9. doi: 10.4085/1062-6050-51.1.03. Epub 2015 Dec 7.


Context: Clinicians and athletes can benefit from field-expedient measurement tools, such as urine color, to assess hydration state; however, the diagnostic efficacy of this tool has not been established.

Objective: To determine the diagnostic accuracy of urine color assessment to distinguish a hypohydrated state (≥2% body mass loss [BML]) from a euhydrated state (<2% BML) after exercise in a hot environment.

Design: Controlled laboratory study.

Setting: Environmental chamber in a laboratory.

Patients or other participants: Twenty-two healthy men (age = 22 ± 3 years, height = 180.4 ± 8.7 cm, mass = 77.9 ± 12.8 kg, body fat = 10.6% ± 4.6%).

Intervention(s): Participants cycled at 68% ± 6% of their maximal heart rates in a hot environment (36°C ± 1°C) for 5 hours or until 5% BML was achieved. At the point of each 1% BML, we assessed urine color.

Main outcome measure(s): Diagnostic efficacy of urine color was assessed using receiver operating characteristic curve analysis, sensitivity, specificity, and likelihood ratios.

Results: Urine color was useful as a diagnostic tool to identify hypohydration after exercise in the heat (area under the curve = 0.951, standard error = 0.022; P < .001). A urine color of 5 or greater identified BML ≥2% with 88.9% sensitivity and 84.8% specificity (positive likelihood ratio = 5.87, negative likelihood ratio = 0.13).

Conclusions: Under the conditions of acute dehydration due to exercise in a hot environment, urine color assessment can be a valid, practical, inexpensive tool for assessing hydration status. Researchers should examine the utility of urine color to identify a hypohydrated state under different BML conditions.

Keywords: diagnostic accuracy; field measurement; hydration; sensitivity; specificity.

MeSH terms

  • Body Mass Index*
  • Color
  • Dehydration / diagnosis*
  • Exercise / physiology*
  • Hot Temperature
  • Humans
  • Male
  • ROC Curve
  • Sensitivity and Specificity
  • Urine*
  • Young Adult