Electrolytes: Potassium Disorders

Hypokalemia (ie, potassium levels less than 3.5 mEq/L) occurs in fewer than 1% of healthy individuals, but is present in up to 20% of hospitalized patients, 40% of patients taking diuretics, and 17% of patients with cardiovascular conditions. Hypokalemia often is asymptomatic; symptoms are more common in older adults. Common symptoms are cardiac arrhythmias and muscle weakness or pain. Management consists of intravenous potassium replacement during cardiac monitoring for patients with marked symptoms, echocardiogram (ECG) abnormalities, or severe hypokalemia (ie, level less than 3.0 mEq/L). Oral replacement is appropriate for asymptomatic patients with less severe hypokalemia. Hyperkalemia (ie, level greater than 5.5 mEq/L) also can cause cardiac arrhythmias and muscle symptoms. Urgent management is warranted for patients with potassium levels of 6.5 mEq/L or greater, if ECG manifestations of hyperkalemia are present regardless of potassium levels, or if severe muscle symptoms occur. Urgent management includes intravenous calcium, intravenous insulin, and inhaled beta agonists. Hemodialysis can be used in urgent situations. For patients with less severe hyperkalemia, renal elimination drugs sometimes are used, as are gastrointestinal elimination drugs. For all patients with hypokalemia or hyperkalemia, drug regimens should be reevaluated and, when possible, hypokalemia- or hyperkalemia-causing drugs should be discontinued.