Introduction:

a low urine volume is a main etiological factor for renal lithiasis (< 1 ml/kg/h). It is commonly assumed that children who report a high fluid intake have a protective urine volume. The purpose of the present study is to assess the habit of fluid intake in healthy schoolchildren and to evaluate its relation with the urinary volume.

Methods:

eighty-four healthy schoolchildren (5-17 years) were asked to categorize their usual fluid intake amount by choosing one of the three options: "low", "normal" or "high" fluid intake. The usual consumed types of beverage were also recorded. Twenty-four-hour urine volume was measured in each child. The results of the questionnaire were compared to that from the urine samples.

Results:

a "low" fluid intake was referred by 23% of children, a "normal" fluid intake by 57% and a "high" fluid intake by 21%. Diuresis values > 1 ml/kg/h were observed in 39% of children (that is: 38.9% of the "low intake" group, 63% of the "normal intake" group and 73.7% of the "high intake" group). Among "normal" and "high" intake groups, a urinary output < 1 ml/kg/h was found in 56% of children.

Conclusions:

a majority of the studied children did not reach the minimum recommended diuresis to prevent urinary lithiasis, even among children who report a high intake of fluids. Strategies aimed at increasing water intake by children population should be highly encouraged.

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