Children, Adolescents and Urine Hydration Indices-A Systematic Literature Review on Athletes and Non-Athletes

Background/Objectives: The importance of adequate hydration in children and adolescents has raised significant attention, both for its health benefits and for its role in supporting cognitive and physical performance. This is particularly important for young athletes who have increased dehydration risk due to high sweat loss and often inadequate water intake. The aim of this review is to systematically assess the hydration status of children and adolescents, including athletes, and to identify notable differences in hydration levels between these groups. Methods: A systematic literature search was conducted following PRISMA guidelines. PubMed, Scopus, and Scholar were searched for articles published between 2004 and 2024 on hydration in children and adolescents, focusing on urinary biomarkers such as urine osmolality, urine specific gravity, and urine color. Two independent reviewers screened the studies, and clinical studies or those involving chronic diseases, disabilities, or missing data were excluded. Results: Fifty-one articles met the inclusion criteria and were categorized into competitive athletes (n = 26) and non-athletes (n = 25). The review revealed that both athletes and non-athletes were frequently dehydrated. Among athletes, 81% of studies reported dehydration, while 69% of studies observed dehydration in non-athlete children. Biomarkers consistently indicated failure to meet recommended hydration guidelines in both groups. Conclusions: Despite existing hydration guidelines, dehydration is prevalent among children and adolescents, irrespective of athletic involvement. This underscores the urgent need for targeted interventions to improve hydration education and practices in schools, homes, and extracurricular settings.