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 (which is when the body doesn't have enough water and other fluids to work properly)
3. Destroyed red blood cells from severe injury or burns
4. Type 1 diabetes

Sometimes a report of high blood potassium isn't true hyperkalemia. Instead, the breaking of blood cells in the blood sample during or shortly after the blood draw may be the cause. The broken cells leak their potassium into the sample.

This raises the amount of potassium in the blood sample, even though the potassium level in your body is okay. You have a repeat blood sample if your healthcare professional thinks this is the cause of the high potassium level in your sample.