What are the signs and symptoms of hyperkalemia?

Hyperkalemia, defined as serum potassium above 5.0 milliequivalents per liter, is dangerous because it affects cardiac conduction. Signs include tall peaked T waves on electrocardiogram, muscle weakness progressing to flaccid paralysis, decreased deep tendon reflexes, nausea, diarrhea, and paresthesias. Severe hyperkalemia above 6.5 can cause widened QRS complex, absent P waves, sine wave pattern, and fatal cardiac arrest. Causes include renal failure, potassium-sparing diuretics, ACE inhibitors, tissue destruction, and acidosis.