How much fluid does the average healthy adult require to maintain fluid balance?

How much fluid does the average healthy adult require to maintain fluid balance?

• A. The same as 15-25 mL/kg/day
• B. 30-40 mL/kg/day
• C. 45-55 mL/kg/day
• D. 60-70 mL/kg/day

Answer: (B)

Maintaining fluid balance in a healthy adult relies on a maintenance fluid intake that covers normal daily losses from urine and insensible losses (skin and respiration). A widely used estimate is about 30–40 mL per kilogram of body weight per day. For example, a 70 kg person would need roughly 2.1–2.8 liters daily, which aligns with common guidance that adults require about 2–3 liters per day. This range balances the typical obligatory losses without overloading the system. Values much lower than this risk underhydration, while values much higher can lead to unnecessary fluid load for many individuals. So, 30–40 mL/kg/day is the best-fit target for maintenance in a healthy adult.

Maintaining fluid balance in a healthy adult relies on a maintenance fluid intake that covers normal daily losses from urine and insensible losses (skin and respiration). A widely used estimate is about 30–40 mL per kilogram of body weight per day. For example, a 70 kg person would need roughly 2.1–2.8 liters daily, which aligns with common guidance that adults require about 2–3 liters per day. This range balances the typical obligatory losses without overloading the system. Values much lower than this risk underhydration, while values much higher can lead to unnecessary fluid load for many individuals. So, 30–40 mL/kg/day is the best-fit target for maintenance in a healthy adult.