The validity urine color scoring at different light conditions to assess low versus high urine concentration

Urine color (Uc) is used to asses urine concentration when lab techniques are not feasible. To compare the accuracy of Uc scoring using four different light conditions and two different scoring techniques with a 7-color Uc chart. Additionally to assess the results' generalizability, a subsample was compared to scores obtained from fresh samples. Descriptive laboratory study. 178 previously frozen urine samples were scored and n=78 samples were compared to its own fresh outcomes. Urine color and accuracy for classifying urine samples were calculated using receiver operating characteristics (ROC) analysis, allowing to compare the diagnostic capacity against a 1.020 urine specific gravity (USG) cut-off and defining optimal Uc cut-off value. Uc was significantly different between light conditions (P