This test measures the amount of potassium in your blood. Potassium is one of several naturally occurring elements in blood called electrolytes. Your body carefully controls the amount of potassium in your blood.
Potassium is critically important for normal heart and nervous system function.
Because potassium is so important, it is the most commonly measured of the body's electrolytes. The potassium level can be helpful in evaluating disorders of the heart, kidneys, adrenal glands, muscles, and digestive system. Some medicines, like digitalis, don't work well if the potassium level isn't normal. You don't need to fast or limit your activity in any way before the test. You may be asked not to take some medications before the tests that can affect the test result.