After you eat a food containing potassium, the mineral travels to your intestines. The intestine absorbs potassium into your bloodstream, where it circulates until it reaches the kidneys. The kidneys decide how much potassium to excrete and how much to keep. When the kidneys excrete too much potassium or the intestine does not absorb enough potassium, a condition called hypokalemia -- the medical term for low potassium levels -- develops.
Significance
Potassium acts as an electrolyte, which means it conducts electrical impulses. These electrical impulses power the heart, control muscle contractions and help food move through the digestive tract. When potassium levels drop below the normal range, it affects the transmission of electrical impulses. This causes problems with the muscles, heart and digestive system. Signs and symptoms of low potassium levels include muscle weakness, fatigue, muscle spasms, muscle-fiber damage and constipation. Severe hypokalemia may lead to paralysis and abnormal heart rhythm.
Identification
If your doctor suspects that you have low potassium, she will order a blood test to confirm this diagnosis. A laboratory technician will determine the amount of potassium in the sample and report the result to your physician. Normal potassium levels range from 3.7 mEq/L -- milliequivalents per liter -- to 5.2 mEq/L.
Causes
Any medication that impairs potassium absorption or increases the amount of potassium excreted in the urine can cause low levels of potassium in the blood. Diuretics, corticosteroids, antacids, insulin, theophylline, laxatives, amphotericin B and fluconazole may cause the amount of potassium in the blood to decrease. Diarrhea, eating disorders, vomiting, excessive sweating and diseases that affect the amount of potassium retained by the kidneys may also cause hypokalemia.
Treatment
Oral supplements and intravenous potassium transfusions increase the amount of potassium in the blood, restoring your potassium level to normal. Physicians prescribe oral supplements for mild potassium deficiency and intravenous potassium for severe deficiency. If you take a medication that affects your potassium level, your doctor may adjust the dosage or instruct you to take a different medication.
Prevention
If you do not have any chronic health condition, consuming foods high in potassium will help you keep your potassium levels within the normal range. The Food and Nutrition Board of the Institute of Medicine recommends 4,700 mg of potassium per day for adults. High-potassium foods to help you reach this daily intake include potatoes, tomatoes, dairy products, chocolate, beets, yams, oranges and bananas. Avoiding overuse of antacids and laxatives may also help you maintain normal potassium levels.
If you have a chronic medical condition that affects your potassium level, talk to your doctor before taking a potassium supplement or adding more potassium-rich foods to your diet. Sometimes the kidneys of those with chronic health problems do not excrete as much potassium as they should. If you have one of these conditions, consuming more potassium could put you at risk of developing elevated potassium levels. High potassium levels can be serious, as they may cause an irregular heartbeat.
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