Sodium and potassium are types of electrolytes. Electrolytes are electrically charged minerals that help control muscle and nerve activity, maintain fluid levels, and perform other important functions in your body. Sodium is important for nerve and muscle function and your body keeps sodium in balance through a variety of mechanisms. Sodium gets into your blood through food and drink and leaves the blood through urine, stool, and sweat. It is important to have the right amount of sodium for your health. Your blood pressure can be raised by too much sodium. Potassium is important for your body to help your heart and muscles function properly. Too high or too low potassium levels may indicate a medical problem.