The most common cause of true high potassium, also called hyperkalemia, is linked to the kidneys. Causes might include:

1. Acute kidney injury
2. Chronic kidney disease

Some medicines or supplements can cause of hyperkalemia, including:

1. Angiotensin-converting enzyme (ACE) inhibitors
2. Angiotensin II receptor blockers
3. Beta blockers
4. Too much potassium supplement

Other causes of hyperkalemia include these conditions:

1. Addison's disease
2. Dehydration — when the body doesn't have enough water and other fluids to work as it should.
3. Destroyed red blood cells from severe injury or burns
4. Type 1 diabetes