Hyperkalemia is the medical term that describes a potassium level in your blood that's higher than normal. Potassium is a nutrient that is critical to the function of nerve and muscle cells, including those in your heart.
Your blood potassium level is normally 3.6 to 5.2 millimoles per liter (mmol/L). Having a blood potassium level higher than 7.0 mmol/L can be dangerous and requires immediate treatment.