Scottsdale, Arizona - Low potassium (hypokalemia) refers to a lower than normal potassium level in your bloodstream. Potassium is a chemical (electrolyte) that is critical to the proper functioning of nerve and muscles cells, particularly heart muscle cells.

Normally, your blood potassium level is 3.6 to 5.2 millimoles per liter (mmol/L). A very low potassium level (less than 2.5 mmol/L) can be life-threatening and requires urgent medical attention.

Low potassium (hypokalemia) has many causes. The most common cause is excessive potassium loss in urine due to prescription water or fluid pills (diuretics). Vomiting or diarrhea or both can result in excessive potassium loss from the digestive tract. Only rarely is low potassium caused by not getting enough potassium in your diet.

Causes of potassium loss leading to low potassium include:

  1. Chronic kidney disease
  2. Diabetic ketoacidosis
  3. Diarrhea
  4. Excessive alcohol use
  5. Excessive laxative use
  6. Excessive sweating
  7. Folic acid deficiency
  8. Prescription water or fluid pills (diuretics) use
  9. Primary aldosteronism
  10. Vomiting
  11. Some antibiotic use

In most cases, low potassium is found by a blood test that is done because of an illness, or because you are taking diuretics. It is rare for low potassium to cause isolated symptoms such as muscle cramps if you are feeling well in other respects.

Low potassium symptoms may include:

  • Weakness
  • Fatigue
  • Muscle cramps
  • Constipation

Abnormal heart rhythms (arrhythmias) are the most worrisome complication of very low potassium levels, particularly in people with underlying heart disease.

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.