AimUrine color (UC) is a practical tool for hydration assessment. The technique has been validated in adults, but has not been tested in children.PurposeThe 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.MethodsA total of 210 children participated (age: 8–14 years, body mass: 43.4 ± 12.6 kg, height: 1.49 ± 0.13 m, body fat: 25.2 ± 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.ResultsMean UC was 3 ± 1 and UOsmo 686 ± 223 mmol kg−1. UC displayed a positive relationship as a predictor of UOsmo (R2: 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 ≥4.ConclusionsThe 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.

Failure to meet TWI-F guidelines increased calculated relative risk of hypohydration in children. Boys between 9 and 13 years are at greater hazard regardless of meeting guidelines and may require greater water intake to avoid elevated urine concentration and ensure adequate hydration.

A drinking pattern based on water and milk was associated with better hydration, as indicated by lower urine osmolality, whereas drinking regular soda and other drinks but not water was associated with inferior hydration.

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Background and objectivesIt has been hypothesized that chronic hypohydration may be associated with vascular stiffness and atherosclerosis mainly driven by increased arginine‐vasopressin, aldosterone, and angiotensin II, however, no study has addressed the issue in humans.MethodsDuring 2011‐2012, 433 men and women (age: 54±10 y, 227; 52% men) were voluntarily enrolled from the general population. Socio‐demographic factors, medical history, physical activity (international physical activity questionnaire) and smoking, were recorded through a face‐to‐face interview. Participants also provided first morning urine sample, analyzed for urine osmolality (Uosm) and completed a validated food frequency questionnaire.Carotid artery Intimal‐Medial‐Thickness (IMT) through ultrasound was also measured by trained cardiologists.ResultsMean IMT was found 0.83±0.32 mm, urine osmolality was: 642±230 mmol/kg and total fluid Intake from beverages was 2,544±884 mL.Multivariable linear regression analysis revealed an independent association between urine osmolality and IMT (B‐coef: 0.0009 and p=0.009), after adjusting for several confounding variables such as age, sex, BMI,fluid intake (from beverages), smoking habits and family history of hypertension and hyperlipidemia. The aforementioned model explained 61.6% of IMT's variability while model's significance was p= 0.06.ConclusionsThe data indicated that hydration status is associated with atherosclerosis.