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Low potassium (hypokalemia)
By Mayo Clinic staffMayo Clinic Health Manager
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Definition
Low potassium level (hypokalemia) occurs when the level of potassium in your blood is lower than normal. Potassium is a nutrient that is critical to the function of nerve and muscles cells, including those in your heart.
Your blood potassium level is normally 3.6 to 4.8 milliequivalents per liter (mEq/L). Having a very low potassium level (less than 2.5 mEq/L) can be life-threatening and requires emergency medical attention.
Low potassium symptoms include:
- Weakness
- Fatigue
- Muscle cramps
- Constipation
- Abnormal heart rhythms (arrhythmias)
Low potassium is usually discovered by your doctor as a blood test result.
Causes
Low potassium (hypokalemia) has many causes. The most common cause of low potassium is excessive potassium loss in urine or from the digestive tract such as due to:
- Certain diuretics — water pills
- Diarrhea
- Eating disorders
- Excessive use of laxatives
- Kidney failure, chronic
- Primary aldosteronism
- Vomiting
Causes
Rarely, low potassium is due to not getting enough potassium in your diet.
When to see a doctor
Low potassium is usually found when your doctor has ordered blood tests to help diagnose a condition you're already experiencing. It's usually not discovered by chance.
Talk to your doctor about what your results mean. You may need to change a medication that's affecting your potassium level, or you may need to treat another medical condition that's causing your low potassium level. Treatment of low potassium is directed at the underlying cause and may include potassium supplements. Don't start taking potassium supplements without talking to your doctor first.
- Rose BD. Causes of hypokalemia. http://www.uptodate.com/home/index.html. Accessed June 24, 2009.
- Rose BD. Diuretic-induced hypokalemia. http://www.uptodate.com/home/index.html. Accessed June 24, 2009.
- Laboratory reference values. Rochester, Minn.: Mayo Foundation for Medical Education and Research. July 1, 2009.
