Doctors use a simple blood test to evaluate if potassium levels are too high, according to Mayo Clinic. Any patient with a potassium level above 5.2 millimoles per liter has high potassium in his blood, which doctors call hyperkalemia. Potassium levels above 7.0 millimoles per liter require immediate medical intervention.
While some people with hyperkalemia have no symptoms, others experience fatigue, tingling, numbness, weakness and nausea, notes Healthline. They may have heart palpitations, skipped heartbeats or difficulty breathing. Extremely high potassium levels can cause paralysis, serious heart problems and death if the heart stops completely.
High potassium levels are often the result of kidney failure or chronic kidney disease, explains Mayo Clinic. Other possible causes of hyperkalemia include substance abuse that leads to muscle breakdown, injuries that lead to red blood cell destruction, Type 1 diabetes or Addison's disease. Prescription medications, such as angiotensin II receptor blockers and angiotensin-converting enzyme inhibitors, also can lead to high potassium levels.
Doctors can treat hyperkalemia caused by kidney problems with hemodialysis, according to Healthline. They also may prescribe diuretics or resin to encourage the body to evacuate excess potassium or gluconate to protect the heart from the effects of hyperkalemia. If the patient's hyperkalemia is a chronic condition, the doctor may recommend a low potassium diet as well.