2-10

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2-10. NORMAL FLUID LOSS

As mentioned earlier, there are four ways the normal healthy body loses fluids daily. People are generally unaware of the loss of fluids since the body does an excellent job of replacing the lost amounts of fluid and electrolytes. It is only when there is a severe loss during illness or injury that the body has difficulty replacing these losses.

a. Perspiration. Perspiration is a constant route for fluid loss. About 650 milliliters of perspiration are lost during a normal day by a healthy person. Along with water, a liter of perspiration has about 45 mEq of

sodium, 4.5 mEq of potassium and 57.5 mEq of chloride. A normal person only becomes aware of the perspiration loss during very strenuous exercise or when the day is very hot. As a general rule, where sodium goes, water follows. That is why there is always sodium on the skin following heavy perspiration.

b. Respiration. Respiration occurs around-the-clock, but most people are not aware that they are exhaling fluid in the form of water vapor every time they breathe. We become aware of the vapor loss during cold weather when the vapor can be seen as it is exposed to low temperatures. About 450 milliliters of fluid are lost during a twenty-four hour period by respiration.

c. Feces. A small amount of fluid is normally contained in the feces. About 100 milliliters of fluid are lost in this manner during a day.

d. Urine. Urination accounts for the greatest fluid loss daily. About 1300 milliliters of urine are excreted by the normal person each day.

e. Total. If these four loss routes are totaled, we find that about 2500 milliliters of fluid are lost and must be replaced daily. See figure 2-7 for a summary.

Figure 2-7. Summary chart for normal fluid loss.

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