 This will be a prospective study of patients presenting to the Emergency Department ED with clinical signs of dehydration. All previously healthy children aged 1 month mo up to 16 years of yo age with vomiting, diarrhea, or poor oral PO intake from presumed gastroenteritis will be eligible for inclusion after obtaining informed consent and assent if applicable. Exclusion criteria will include a history of cardiac or renal disease, diabetes mellitus DM, malnutrition or failure to thrive FTT, and any malabsorptive disorder or short gut syndrome . Children will further be excluded if they are clinically unstable, requiring immediate life saving interventions or if no parent or legal guardian is available for consent. 