In 21 healthy children aged 6–11 years water balance studies were performed for 3 days at home. Water intake was assessed from dietary records based on the precise weighing method and water loss was calculated from repeated measurements of body weight and urine collection. Mean values ( ± SD) of all parameters of water balance are presented. Water intake from food and drinks without metabolic water of 43.0 ± 11.5 g/kg/day or 0.78 ± 0.17g/kcal (0.19 ± 0.04 g/kJ) resulted in a urine volume of 22.5 ± 7.7 g/kg/day and an osmolality of 24-hour urine samples of 756 ± 199 mosm/kg. From these data water intake seems to be low in these children. In school-aged children water intake from food and drinks of 1 ml/kcal (0.24 ml/kJ) as recommended for adults (Recommended dietary allowances, 1980) would seem adequate, theoretically resulting in a urine volume of 35 ± 14 g/kg/day and urine osmolality of 516 ± 182 mosm/kg based on the data in our children.

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