Water intake and urine osmolarity in Spanish school children aged 7-11 years.

Abstract

Background: Dehydration is acutely associated with a wide variety of adverse outcomes in healthy adults and children. Objective: To analyze the hydration status assessed by water intake and urine osmolarity in a group of Spanish school children. Method: This is a cross-sectional study including 278 schoolchildren aged 7-11 years selected from various Spanish provinces. All children completed a 3-day “food and drink record” and 262 provided a 24-h urine sample. Total intake and dietary sources of water were calculated using DIAL software and osmolarity was calculated using urine sodium, potassium and urea. Results: Mean total water intake was 1,405±437.9 mL/day and 86.3% of the children did not meet adequate intakes of water (IoM, 2005). No differences in total intake and dietary sources of water were observed by sex. Elevated urine osmolarity (>800 mOsm/L) was observed in 50.6% of participants. Boys presented higher urine osmolarity than girls (827.9±208.5 mOsm/L vs. 765.6±198.1 mOsm/L; p<0.05). A linear correlation was found between urine osmolarity and food moisture (excluding beverages) (r=0.147; p<0.05) and soft drinks moisture (r=0.264; p<0.05). In an analysis by sex group, the association between urine osmolarity and food moisture remained only in boys (r=0.237; p<0.01). Conclusion: The present study reports a high prevalence of elevated urine osmolarity in children, especially in boys. Elevated urine osmolarity was associated with food moisture (excluding beverages) and water from soft drinks. This study was supported by a UCM Research Project (PR6/13-18866) and with the Grant UCM-Santander Research Group Program (Ref. GR3/14).