Harvard Heart Letter

Ask the doctor: Is high potassium a problem?

Q. You have written about low potassium in the blood and ways to improve it, but I never read about too much potassium in the blood. Can you tell me why it happens and what is done about it?

A. Relatively few people develop high levels of potassium in the blood, since the kidneys are normally quite effective in clearing this mineral from the bloodstream. A normal blood potassium measurement is 3.7 to 5.2 milliequivalents per liter.

High potassium or, as doctors call it, hyperkalemia, can occur for several reasons. Problems with the kidneys, such as kidney failure or glomerulonephritis, can elevate potassium in the bloodstream. So can taking medications that cause the kidneys to hold on to potassium. These include potassium-sparing diuretics such as spironolactone (Aldactone, generic) and triamterene (Dyrenium, generic); ACE inhibitors; angiotensin-receptor blockers (ARBs); and nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen. Two other causes of high potassium include using a salt substitute that contains potassium or taking a potassium supplement.

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