what causes high potassium levels in blood
High potassium in the blood (hyperkalemia) usually happens when the body can’t get rid of potassium properly, too much potassium suddenly enters the blood, or something makes potassium move out of cells into the bloodstream.
What is “high potassium”?
- Doctors usually call potassium “high” when blood levels are above about 5.0–5.5 mEq/L.
- Mild elevations may cause no symptoms, but higher levels can lead to dangerous heart rhythm problems and muscle weakness.
Main causes: kidneys and hormones
The kidneys are the main organ that keep potassium in balance.
- Acute kidney injury (sudden kidney failure).
- Chronic kidney disease or advanced kidney damage of any cause.
- Missing or shortening dialysis sessions in people on dialysis.
- Low levels or poor action of aldosterone , a hormone that tells kidneys to excrete potassium (for example Addison’s disease, some rare genetic conditions).
Medicines and supplements that raise potassium
Many common drugs can reduce potassium excretion or shift potassium out of cells.
Examples include:
- ACE inhibitors (like lisinopril) and ARBs (like losartan) used for blood pressure or heart/kidney protection.
- Potassium‑sparing diuretics (such as spironolactone, eplerenone, amiloride).
- Some beta‑blockers.
- Certain blood pressure or heart medicines (including some renin inhibitors, aldosterone blockers, and others).
- Potassium supplements or “salt substitutes” that use potassium instead of sodium.
- Some herbal products and IV fluids containing potassium, especially in people with kidney problems.
Too much intake or not enough out
On their own, healthy kidneys usually handle a high‑potassium meal, but problems arise when intake is high and kidney function or hormones are impaired.
- Eating lots of high‑potassium foods (bananas, oranges, tomatoes, potatoes, some juices) in someone with kidney disease.
- Heavy use of potassium‑based salt substitutes.
- Severe or chronic constipation, which can reduce potassium elimination through the gut.
Conditions that shift potassium out of cells
Some illnesses don’t add potassium to the body but move it from inside cells into the blood.
- Uncontrolled diabetes and lack of insulin (for example in diabetic ketoacidosis), which prevents potassium from entering cells.
- Metabolic acidosis (when the blood becomes more acidic), which can occur with severe dehydration, sepsis, or poor circulation.
- Large tissue breakdown:
- Rhabdomyolysis (severe muscle breakdown from crush injury, extreme exercise, certain drugs).
* Severe burns or major trauma.
* Tumor lysis syndrome during chemotherapy, when many cancer cells break down quickly.
- Some rare inherited conditions like hyperkalemic periodic paralysis.
Other medical problems linked to high potassium
Several common chronic diseases increase risk.
- Diabetes (especially if poorly controlled or with kidney damage).
- Heart failure and certain heart diseases, which can affect kidney blood flow and hormone balance.
- Liver disease or severe volume depletion (dehydration, major bleeding), which reduce kidney perfusion.
- Blood disorders with increased cell destruction, such as hemolytic anemia.
- Internal bleeding in the gut (stomach or intestines), where absorbed blood releases potassium.
“False” high potassium (lab artifact)
Sometimes a blood test looks high even though the true level in the body is normal.
- Difficult blood draw causing lots of red cell breakage (hemolysis) in the tube.
- Blood sitting too long before being processed or being shaken vigorously.
- Very high white blood cell or platelet counts can rarely cause spurious readings.
This is called pseudohyperkalemia , and doctors may repeat the test or use a different sampling method to confirm.
When to worry and what to do
High potassium can be life‑threatening if not treated promptly, especially if you have heart disease or kidney problems.
- Seek emergency care immediately if you have high potassium plus chest pain, feeling like your heart is “fluttering,” severe muscle weakness, or trouble breathing.
- Never stop or change prescription medicines on your own; talk to your doctor or pharmacist if you’re concerned your drugs might raise potassium.
- If you have kidney disease or are on dialysis, ask your care team for a kidney‑friendly eating plan and which salt substitutes or supplements to avoid.
This information is general and cannot replace personalized medical advice. Always discuss your lab results and symptoms with a qualified health professional.
TL;DR: High potassium levels in blood are most often caused by kidney problems, certain medications, hormone issues, high potassium intake in people with kidney disease, and conditions that cause potassium to leak out of cells, such as uncontrolled diabetes, major tissue injury, or severe illnesses.