Validation of a urine color scale for assessment of urine osmolality in healthy children

Aim Urine color (UC) is a practical tool for hydration assessment. The technique has been validated in adults, but has not been tested in children. Purpose The purpose of the study was to test the validity of the urine color scale in young, healthy boys and girls, as a marker of urine concentration, investigate its diagnostic ability of detecting hypohydration and examine the ability of children to self-assess UC. Methods A total of 210 children participated (age: 8-14 years, body mass: 43.4 +/- A 12.6 kg, height: 1.49 +/- A 0.13 m, body fat: 25.2 +/- A 7.8 %). Data collection included: two single urine samples (first morning and before lunch) and 24-h sampling. Hydration status was assessed via urine osmolality (UOsmo) and UC via the eight-point color scale. Results Mean UC was 3 +/- A 1 and UOsmo 686 +/- A 223 mmol kg(-1). UC displayed a positive relationship as a predictor of UOsmo (R (2): 0.45, P < 0.001). Based on the receiver operating curve, UC has good overall classification ability for the three samples (area under the curve 85-92 %), with good sensitivity (92-98 %) and specificity (55-68 %) for detecting hypohydration. The overall accuracy of the self-assessment of UC in the morning or the noon samples ranged from 67 to 78 %. Further threshold analysis indicated that the optimal self-assessed UC threshold for hypohydration was a parts per thousand yen4. Conclusions The classical eight-point urine color scale is a valid method to assess hydration in children of age 8-14 years, either by researchers or self-assessment.