Hyperkalemia: What causes high potassium?

My doctor says I have high potassium. What causes this?

- Jim / California

Mayo Clinic hematologist Ruben Mesa, M.D., and colleagues answer select questions from readers.

Answer

The most common cause of high potassium (hyperkalemia) is impaired kidney function, such as due to acute or chronic kidney failure. Other causes of hyperkalemia include:

Certain medications, such as angiotensin-converting enzyme (ACE) inhibitors
Hormone deficiencies, including adrenal failure (Addison's disease)
Destruction of red blood cells due to severe injury or burns
Excessive use of potassium supplements
Alcoholism or heavy drug use that causes rhabdomyolysis, a breakdown of muscle fibers that results in the release of potassium into the bloodstream

Most of the potassium in your body is within your cells. As a result, the amount of potassium in your red blood cells is much greater than in the liquid part of your blood (plasma or serum). Your kidneys control the excretion of potassium in your urine.

True hyperkalemia is a serious and potentially life-threatening disorder. It can cause:

Muscle fatigue
Weakness
Paralysis
Abnormal heart rhythms (arrhythmias)
Nausea

Sometimes a report of high blood potassium isn't true hyperkalemia. Instead it may be caused by the rupture of red blood cells in the blood sample during or shortly after drawing the sample. The ruptured cells leak their potassium into the serum. This falsely elevates the amount of potassium in the blood sample, even though the potassium level in your body is actually normal. When this is suspected, a repeat blood sample is obtained.