<P> Where (Na) t = target sodium concentration (usually 140 mEq / L), and (Na) m = measured sodium concentration . </P> <P> The resultant value is the approximate volume of free water required to correct a hypernatremic state . In practice, the value rarely approximates the actual amount of free water required to correct a deficit due to insensible losses, urinary output, and differences in water distribution among patients . </P> <P> Water in the animal body performs a number of functions: as a solvent for transportation of nutrients; as a medium for excretion; a means for heat control; as a lubricant for joints; and for shock absorption . </P> <P> The usual way of adding water to a body is by drinking . Water also enters the body with foods, especially those rich in water, such as plants, raw meat, and fish . </P>

Where does fluid in the body come from