Fluid intake and urine output should relate in which way?

• A. Fluid intake should be double the urine output.
• B. Fluid intake should be approximately equal to the urine output.
• C. Fluid intake should be half the urine output.
• D. Fluid intake should be inversely proportional to the urine output.

Answer: (B)

Maintaining fluid balance means that what you take in as drinking (plus metabolic water from food) roughly matches what you lose, so the body stays hydrated without gaining or losing excess water. Urine is the main route the body uses to lose water, and insensible losses through skin and lungs are always there but relatively steady and smaller. In a healthy person at steady state, fluid intake should be approximately equal to urine output, allowing for those small non-urinary losses. The other options describe situations that would create a persistent water surplus or deficit (drinking much more or much less than you urinate, or being inversely related), which isn’t how normal hydration works.