A nurse is assisting with the admission of a 2-year-old toddler who has acute gastroenteritis. Which of the following actions should the nurse take first?

A. Collect a stool sample from the toddler: This is important but not the priority. Dehydration status must be assessed first. B. Determine if the toddler is voiding: Assessing for urination helps evaluate hydration status and guides fluid replacement. C. Initiate isotonic fluids with 20 mEq/L potassium chloride: Potassium should not be added until kidney function and voiding are confirmed. D. Request evaluation of the toddler’s serum electrolytes: This is important but comes after assessing hydration and kidney function.