What Is Hyperkalemia? High Potassium

What it means

Hyperkalemia means there is too much potassium in the blood. Potassium is needed for nerves and muscles, especially the heart, but too much can upset the heart's rhythm. It often causes no symptoms, but can cause weakness, tingling or an irregular heartbeat. Palpitations, severe weakness or fainting need urgent medical help.

Labels list hyperkalemia for medicines that make the body keep potassium, such as ACE inhibitors, angiotensin II receptor blockers, potassium-sparing diuretics and potassium supplements. The risk is higher in people with kidney disease or diabetes, and when these medicines are combined. The warning is why your doctor may check potassium with blood tests, and why some labels say to avoid potassium-containing salt substitutes unless advised.

Hyperkalemia (high potassium) is the opposite of hypokalemia (low). A high result is sometimes caused by the blood sample itself, for example if red cells burst in the tube (a hemolyzed sample), so it may be repeated.

Where you may see it

• Labels for ACE inhibitors, ARBs and potassium-sparing diuretics
• Blood test reports as 'Potassium (K)' with an H flag
• Kidney clinic letters