High potassium in the blood (hyperkalemia) is most often caused by kidney problems, certain medications, or conditions that make potassium leak out of cells too quickly.

What “high potassium” means

  • Hyperkalemia usually means a blood potassium level above about 5.0–5.5 mEq/L, which can affect heart rhythm and muscles.
  • Mild elevations may cause no symptoms, but higher levels can lead to dangerous heart rhythm changes, weakness, or even paralysis.

Major medical causes

  • Kidney disease or injury : Acute kidney injury and chronic kidney disease reduce the kidneys’ ability to remove extra potassium, making this the most common true cause.
  • Hormone problems : Low aldosterone (as in Addison disease or certain adrenal disorders) or insulin deficiency in diabetes can keep potassium from being excreted or moved into cells.
  • Heart failure and severe liver disease : Reduced blood flow to the kidneys and use of specific heart medicines can raise potassium.

Medication and supplement causes

  • Blood pressure and heart drugs such as ACE inhibitors, ARBs, potassium‑sparing diuretics, and some beta blockers can raise potassium levels.
  • Overuse of potassium supplements or salt substitutes that contain potassium can push levels into the dangerous range.
  • Certain other drugs, including some chemotherapy agents and the antibiotic combination sulfamethoxazole‑trimethoprim, are also linked with hyperkalemia.

Conditions that release potassium from cells

  • Severe tissue damage, such as major burns, crush injuries, or muscle breakdown (rhabdomyolysis), releases large amounts of potassium into the bloodstream.
  • Uncontrolled high blood sugar, heavy alcohol use, or severe infections can contribute to muscle breakdown or shifts of potassium from inside cells to the blood.
  • Metabolic acidosis (blood becoming more acidic) can shift potassium out of cells and increase blood levels.

Lab artifact: not always “real”

  • Sometimes a test shows high potassium even though the level in the body is normal; this “pseudohyperkalemia” often happens when blood cells are damaged during the blood draw (hemolysis) or with very high platelet or white blood cell counts.
  • In those cases, repeating the test with careful sampling is needed before assuming there is true hyperkalemia.

Important: High potassium can be life‑threatening, especially with heart disease or kidney problems. If a lab result shows high potassium or there are symptoms like chest pain, palpitations, or sudden weakness, urgent medical evaluation is needed.

Information gathered from public forums or data available on the internet and portrayed here.