Sodium Potassium

This test is performed when symptoms of a sodium imbalance are present, or when disorders associated with abnormal sodium levels develop. Sodium (Na+) is the major positive ion in the fluids outside of cells. The concentration of sodium inside cells is only about 5 mEq/L compared with 140 mEq/l outside. In normal people, taking potassium supplements or potassium containing drugs is of no consequences, because the kidneys effciently dispose of excess potassium.