With hyperkalemia, symptoms may be absent and when present they are not specific. In view of its possible dangerous outcome, early diagnosis becomes important.

A suspicion of hyperkalemia can be obtained from the medical history, symptoms if any and physical examination.

Confirmation can be obtained only from the lab tests and ECG changes.


  • Medical history of the patient includes gathering information relevant information about the patient.
  • Regarding his eating habits and exclusive affinity to certain foods that could be high in potassium.
  • Whether he is a heart patient or having hypertension or diabetes and is on heart healthy diet with low sodium and high potassium foods
  • Whether he/she is taking any drugs that could cause this condition.
  • Whether he is on potassium supplements, salt substitutes, and such additives that are high in potassium.
  • Whether he has or had any kidney problem.

Rule out other causes of hyperkalemia as explained.

Physical examination

  • Vital signs are usually normal. These include blood pressure, pulse, respiratory rate and temperature.
  • General finding may show muscle weakness and fatigue.
  • Slow heart rate (bradycardia)
  • Tachypnea (rapid breathing) due to respiratory muscle weakness.
  • Depressed or absent deep tendon reflexes.

Diagnostic tests

  • Serum potassium to determine its level in blood.
  • Kidney function tests to rule out kidney insufficiency.
  • In case of renal failure, serum calcium is checked because hypocalcemia can cause cardiac rhythm changes
  • Complete blood count (CBC) with platelet count
  • A comprehensive metabolic panel is a blood test, which measures your sugar (glucose) level, electrolyte and fluid balance, kidney function, and liver function.
  • Arterial blood gases to rule out acidosis
  • Serum creatinine phosphokinase (CPK) and calcium level measurements to rule out rhabdomyolysis (breakdown of skeletal muscle tissue).
  • Urine studies for potassium, sodium and osmolality

ECG changes in hyperkalemia

Electrocardiogram (ECG) is done to check for changes indicative of hyperkalemia. These include the peaked T-wave, flattened P-wave with prolonged PR interval, or a totally absent P-wave, and wide QRS complex. St depression is another important feature.

These changes are more indicative of potassium levels of 6.5-8.0 mEq/L. These ECG changes reverse with the success of the appropriate treatment.

However, a normal EKG may be seen even with severe hyperkalemia.