Athletes’ Self-Assessment of Urine Color Using Two Color Charts to Determine Urine Concentration

Abstract

Our objective was to determine self-reported accuracy of an athletic population using two different urine color (Uc) charts (8-color vs. 7-color Uc chart). After approval by the Institutional Review Board, members of an athletic population (n = 189, 20 (19–22) year old student- or tactical athletes and coaches, with n = 99 males and n = 90 females) scored their Uc using two charts. To determine the diagnostic value of Uc, results were compared with urine concentration (osmolality and urine specific gravity, USG). Uc was scored slightly darker with the 8-color vs. 7-color Uc chart (2.2 ± 1.2 vs. 2.0 ± 1.2, respectively, p < 0.001), with a moderate correlation between charts (r = 0.76, 95% CI: 0.69–0.81). Bland-Altman analysis showed a weak reporting bias (r = 0.15, p = 0.04). The area under the curve for correct urine sample classification ranged between 0.74 and 0.86. Higher accuracy for both methods was found when Uc scores were compared to USG over osmolality, indicated by 4.8–14.8% range in difference between methods. The optimal Uc cut-off value to assess a low vs. a high urine concentration for both Uc charts varied in this study between 1 and ≤2 while accuracy for charts was similar up to 77% when compared to USG.

Analysis of the Distribution of Urine Color and Its Relationship With Urine Dry Chemical Parameters Among College Students in Beijing, China – A Cross-Sectional Study

“…The scale ranged from light yellow to dark amber to analyze the correlation of Ucol with hydration ( 15 – 17 , 19 – 21 ). It is an effective method that is highly practical for assessing hydration either for researchers or self-assessment ( 17 , 22 , 23 ). However, this subjective tool has certain methodological limitations, including its lack of objective quantification ( 24 ) and the limited content in its interval scale, as it is without continuous numerical value [Color 1, 255255199; Color 2, 255251186; Color 3, 255249164; Color 4, 255232077; Color 5, 245227157; Color 6: 229201135; Color 7, 207159072; Color 8, 147140074 (RGB, Södersjukhuset Photographic Laboratory, Stockholm, Sweden)] ( 20 ).…”

Validity of Urine Color Scoring Using Different Light Conditions and Scoring Techniques to Assess Urine Concentration

“…The second method involved a color scoring box constructed in our lab 20 . This box was constructed to standardize the distance from the observer to the sample, and the way the urine sample was positioned in relation to the light for each separate light condition (14 inches) as previously reported 21 . Technicians looked through the box while comparing the color they perceived with the colors on the 7-color Uc chart positioned directly aside the box.…”

“…The 7-color Uc developed by Wardenaar & Bacalzo in 2019, was based on a selection of 96 previously collected urine samples 20 . Color prints as previously described were made on a 43.2x27.9 cm (17x11 inch) white paper with a gloss finish 21 .…”

“…The sensitivity analysis was based on only one light condition (LED panel) using the Uc scoring box technique, because this was the only way the subsample of fresh urine samples was scored for Uc before freezing. It can be seen as a limitation that the Uc scoring was compared with USG and not with urine osmolality, although USG has shown to correlate strongly up to r= 0.97 with urine osmolality 21 . Another limitation is that the study used randomly selected spot urine samples provided at different times of the day, yet previous data from our lab indicate that when stratifying urine collections for morning vs. other moments during the day, no substantial effects were found on urine color scoring accuracy 6 .…”

“…This study suggests that 30 mL urine samples lighted from underneath by a small LED flashlight results in the highest number of correctly classified urine samples, while using a modified urine color cut-off value. Previous research suggests that the cutoff value for fresh urine samples while scored using bright LED light was equal to 1, suggesting that samples with a urine color score ≥2 indicated a USG ≥1.020 21 .…”