Validation of Urine Color Charts as an Appropriate Tool to Self-Report Hydration Status when Compared to Urine Specific Gravity and Urine Osmolality

Water is an essential nutrient that is often overlooked. As a result of this hydration status is often forgotten as well. Becoming hypohydrated puts athletes at risk of decreased performance and potentially life-threatening heat illness. Being able to self-assess hydration status is may be instrumental in helping athletes safely optimize performance. Therefore, this study investigated, 1) the ability of an athletic population vs. trained investigators to self-diagnose underhydration, 2) the diagnostic ability of urine color (Ucol) charts as a method for diagnosing underhydration, and 3) the accuracy of participant and investigator assessments. Members of an athletic population each provided a urine sample and scored samples using both the traditional 8-color and newly developed 7-color Ucol chart. Investigators then scored the samples using the same methods. To determine the diagnostic value of the Ucol charts, Ucol scores were compared to concentration measures of Urine Specific Gravity (USG) and Urine Osmolality (Uosm). Differences in participant and investigator scores were compared using Mann-Whitney U and Spearman’s Correlation. Bland-Altman plots were drawn to assess individual differences in reporting against the mean of the two methods. Receiver Operating Characteristic (ROC) analysis was used to both determine the ability of both charts to diagnose underhydration and to determine how well participants and investigators can determine their level of hydration. Athletes reported Ucol significantly lighter compared to investigators. Investigators showed no difference in reporting between the two charts but, athletes reported less than a color shade difference. The charts performed fair (8-color) to good (7-color) at diagnosing hypohydration. Athletes reported with less accuracy compared to investigators, and Ucol classification was found to be more accurate when compared to USG. Ucol charts are a practical tool to determine hydration status. Ucol scoring is similar regardless of the type of chart used. Trained investigators reported with slightly higher accuracy on both charts compared to untrained athletes. Athletes score Ucol fair to good in comparison to investigators. Ucol scoring is similar regardless of the type of chart used. The diagnostic ability of both Ucol charts is good in relation to USG. With education, athletes may be able to improve scores.