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

Abstract

Context: Clinicians and athletes can benefit from fieldexpedient 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 ¼ 22 6 3 years, height ¼ 180.4 6 8.7 cm, mass ¼ 77.9 6 12.8 kg, body fat ¼ 10.6% 6 4.6%).Intervention(s): Participants cycled at 68% 6 6% of their maximal heart rates in a hot environment (368C 6 18C) 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 ¼ 0.951, standard error ¼ 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 ¼ 5.87, negative likelihood ratio ¼ 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.

Biomarkers in Sports and Exercise: Tracking Health, Performance, and Recovery in Athletes

“…Based on the 8-point urine color scale developed by Dr. Lawrence Armstrong, the threshold of dehydration is color 4, with 1 being the lightest and 8 the darkest color. A urine color of 5 or above is consistently and reliably associated with dehydration ( 83 ).…”

Distinguishing Low and High Water Consumers—A Paradigm of Disease Risk

“…Pale yellow or straw colored urine indicates a state of euhydration [46]. A validated 8-point urine color chart [9,145,146] is available at www.hydrationcheck.com. Because the interpretation of hydration status varies across a typical day, depending on which technique is used, it is wise to self-assess hydration status using two or more of these techniques [25].…”

The Effect of Hydration on Urine Color Objectively Evaluated in CIE L*a*b* Color Space

“…Urine color has been shown to be a viable marker of hydration status in healthy adults (1,2). This is evidenced by the significant correlations (r > 0.70) of urine color with several established physiological measures of whole-body hydration, including urine osmolality and urine-specific gravity (1,(3)(4)(5).…”