If fluid loss is greater than fluid gain (for example if the patient vomits and has diarrhea), the patient is said to be in negative fluid balance. In this case, fluid is often given to compensate for the loss.

intravenously

On the other hand, a positive fluid balance (where fluid gain is greater than fluid loss) might suggest a problem with either the kidney or cardiovascular system.

The majority of fluid output occurs via the , approximately 1500 ml/day (approx 1.59 qt/day) in the normal adult resting state.[12][13]

urine

Some fluid is lost through (part of the body's temperature control mechanism) and as water vapor in exhaled air. These are termed "insensible fluid losses" as they cannot be easily measured. Some sources say insensible losses account for 500 to 650 ml/day (0.5 to 0.6 qt.) of water in adults,[12][14] while other sources put the minimum value at 800 ml (0.8 qt.).[15] In children, one calculation used for insensible fluid loss is 400 ml/m2 body surface area.

perspiration

In addition, an adult loses approximately 100 ml/day of fluid through .[12][16]

feces

For females, an additional 50 ml/day is lost through vaginal secretions.

Drinking water