This test measures the amount of sodium in your blood.
Sodium is one of several naturally occurring elements in blood called electrolytes.
You may already be familiar with sodium as sodium chloride, or table salt. Your body carefully controls the amount of sodium in your blood. The sodium level can be helpful in evaluating disorders of the kidneys, adrenal glands, muscles and nerves. 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 that can affect results before the test.