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

J Athl Train. 2022 Feb 1;57(2):191-198. doi: 10.4085/1062-6050-0389.21.


Context: Urine color (Uc) is used to asses urine concentration when laboratory techniques are not feasible.

Objective: To compare the accuracy of Uc scoring using 4 light conditions and 2 scoring techniques with a 7-color Uc chart. Additionally, to assess the results' generalizability, a subsample was compared with scores obtained from fresh samples.

Design: Descriptive laboratory study.

Samples: A total of 178 previously frozen urine samples were scored, and 78 samples were compared with their own fresh outcomes.

Main outcome measure(s): Urine color and accuracy for classifying urine samples were calculated using receiver operating characteristics analysis, allowing us to compare the diagnostic capacity against a 1.020 urine specific gravity cutoff and defining optimal Uc cutoff value.

Results: Urine color was different among light conditions (P < .01), with the highest accuracy (80.3%) of correct classifications of low or high urine concentrations occurring at the brightest light condition. Lower light intensity scored 1.5 to 2 shades darker on the 7-color Uc scale than bright conditions (P < .001), but no further practical differences in accuracy occurred between scoring techniques. Frozen was 0.5 to 1 shade darker than freshly measured Uc (P < .004), but the values were moderately correlated (r = 0.64). A Bland-Altman plot showed that reporting bias mainly affected darker Uc without affecting the diagnostic ability of the method.

Conclusions: Urine color scoring, accuracy, and Uc cutoff values were affected by lighting condition but not by scoring technique, with greater accuracy and a 1-shade-lower Uc cutoff value at the brightest light (ie, light-emitting diode flashlight).

Keywords: assessment of hydration status; fluid intake monitoring; hydration education; hydration status.

MeSH terms

  • Color
  • Dehydration*
  • Humans
  • ROC Curve
  • Research Design
  • Urinalysis*
  • Urine