Hypokalemia and Hyperkalemia

Hypokalemia and hyperkalemia are common in the inpatient population. Serum potassium concentration is used to diagnose hypokalemia and hyperkalemia. Most potassium is intracellular and has a normal concentration of approximately 150 mmol (mEq)/L. Serum potassium has a normal concentration of 3.5 to 5.0 mmol/L. Hypokalemia is defined as a serum potassium concentration less than 3.5 mmol/L, and hyperkalemia is defined as a serum potassium concentration of higher than 5.0 mmol/L. In this article, the epidemiology, pathophysiology, clinical features, and treatment of hypokalemia and hyperkalemia are discussed. After treatment of severe hypokalemia or hyperkalemia, close monitoring of serum potassium is indicated.