Hyperkalemia refers to an elevated serum potassium level (usually >5.5 mEq/L). Severe hyperkalemia, defined as serum potassium ≥6.5 mEq/L or 5.6–6.4 mEq/L with symptoms or EKG changes, requires immediate treatment. Initial treatment with calcium gluconate will stabilize the cardiac myocyte membrane, while other therapies such as insulin and beta agonists promote intracellular uptake. For patients with normal or moderately reduced renal function, loop diuretics and gastrointestinal binding resins may be used to eliminate potassium. In the presence of advanced renal failure, or when conservative therapies fail, hemodialysis is needed and nephrology consultation must be ordered. A thorough investigation into the causes of the hyperkalemia will help to tailor further treatment. Assess for high potassium intake (although this alone does not result in hyperkalemia), release from intracellular stores (acidosis or cell injury), and impaired potassium excretion (renal failure or impaired aldosterone action).