Abstract：
Changes in hydration status occur throughout the day affecting physiological and behavioural functions. However, little is known about the hydration status of free-living Japanese children and the seasonality of this response. We evaluated hydration status estimated by urine osmolality (Uosm) in 349 children (189 boys and 160 girls, 9.5 ± 2.6 years, range: 6-15 years) upon waking at home and during a single school day in spring (April) and summer (July). Further, we assessed the efficacy of employing self-assessment of urine colour (UC; based on an 8-point scale) by children to monitor their hydration status. Early morning Uosm was greater in the spring (903 ± 220 mOsm L-1; n = 326) as compared to summer (800 ± 244 mOsm L-1; n = 125) (P = 0.003, paired t test, n = 104). No differences, however, were observed in Uosm during the school day (P = 0.417, paired t test, n = 32). While 66% and 50% of children were considered underhydrated (Uosm ≥ 800 mOsm L-1) upon waking in the spring and summer periods, respectively, more children were underhydrated (∼12%) during the school day. Self-reported UC was similar between seasons as assessed in the morning and school day (P ≥ 0.101, paired t test), which differed from the pattern of responses observed with Uosm. We showed that a significant number of Japanese children are likely underhydrated especially in the spring period. Children do not detect seasonal changes in hydration from self-assessed UC, limiting its utility to manage hydration status in children.
摘要：
水合状态的变化全天发生,影响生理和行为功能。然而,对自由生活的日本儿童的水合状态以及这种反应的季节性知之甚少。我们评估了349名儿童（189名男孩和160名女孩，9.5±2.6年，范围：6至15年）在家中醒来以及春季（4月）和夏季（7月）的单个学校日。Further,我们评估了采用尿液颜色自我评估的功效(UC，基于8点量表)由儿童监测他们的水合状态。与夏季（800±244mOsmL-1；n=125）相比，春季（903±220mOsmL-1；n=326）的清晨尿湿较高（P=0.003，配对t检验，n=104）。没有差异,然而,在上学期间观察到Uosm(P=0.417，配对t检验，n=32)。虽然在春季和夏季醒来时，有66％和50％的儿童被认为水分不足（Uosm≥800mOsmL-1），更多的孩子在上学期间水分不足(12%)。自我报告的UC在早晨和上学日评估的季节之间相似（P≥0.101，配对t检验），这与用Uosm观察到的反应模式不同。我们发现，大量日本儿童可能水分不足，尤其是在春季。儿童没有从自我评估的UC中检测到水合的季节性变化，限制其效用来管理儿童的水合状态。
