It is important to keep a balance of electrolytes in your body, because they affect the amount of water in your body, blood acidity (pH), muscle action, and other important processes. You lose electrolytes when you sweat, and you must replace them by drinking fluids. Electrolytes exist in the blood as acids, bases, and salts (such as sodium, calcium, potassium, chlorine, magnesium, and bicarbonate). They can be measured by laboratory studies of the blood.