Having too much or too little potassium in the body can have very serious consequences.

Because so many foods contain potassium, too little potassium (potassium deficiency) is rarely caused by inadequate diet. However, even a moderate reduction in the body's potassium levels can lead to salt sensitivity and high blood pressure. The recommended dietary intake of 4.7 gm or higher can slightly lower blood pressure.

A deficiency of potassium (hypokalemia) can happen in people with certain diseases or as a result of taking diuretics (water pills) for the treatment of high blood pressure or heart failure. Additionally, many medications -- such as diuretics, laxatives, and steroids -- can cause a loss of potassium, which occasionally may be very severe. You should have your blood levels of potassium checked from time to time if you take any of these medicines. Diuretics are probably the most common cause of hypokalemia.

A variety of conditions can cause potassium loss from the body. The most common are vomiting and diarrhea. Several rare kidney and adrenal gland disorders may also cause low potassium levels.

For more information on potassium deficiency, see the article on hypokalemia.

Too much potassium in the blood is known as hyperkalemia. Some common causes of this are reduced renal (kidney) function, an abnormal breakdown of protein, and severe infection. The most common cause of hyperkalemia is reduced kidney function, especially in people receiving dialysis for kidney failure. Certain medicines affect the body's ability to get rid of potassium. These include potassium sparing diuretics and angiotensin converting enzyme (ACE) inhibitors.

For more information on increased potassium levels, see the article on hyperkalemia.