A nurse in an emergency department is caring for an infant who has a 2-day history of vomiting and an elevated temperature. Which of the following should the nurse recognize as the most reliable indicator of fluid loss?

A. Skin integrity: While skin turgor and moisture can provide clues about hydration status, they are subjective and less reliable in infants due to their naturally elastic skin and fat distribution. B. Body weight: Changes in body weight are the most accurate and objective indicator of fluid loss or gain in infants. A weight loss of even a few percentage points can reflect significant dehydration. C. Respiratory rate: An increased respiratory rate may occur due to metabolic acidosis from dehydration but is influenced by many factors like fever or infection, making it a less specific indicator of fluid loss. D. Blood pressure: Blood pressure often remains normal due to compensatory mechanisms until dehydration is severe or shock develops. It is a late and less sensitive sign of fluid volume depletion in infants.