The most common cause of high potassium is kidney disease.

Other causes of high potassium include:

  • Dehydration
  • Some medicines
  • Uncontrolled diabetes
  • Injuries that cause severe bleeding
  • Some rare diseases

If you have kidney disease, you are at risk for high potassium because your kidneys cannot remove the extra potassium in your blood. Instead of leaving your body through your urine, the extra potassium in your blood travels through your kidneys and back into your bloodstream. Over time, more and more potassium can build up in your blood.