Possible Metoprolol-Induced Hyperkalemia

Hyperkalemia can be a life-threatening event due to the risk of potentially fatal arrhythmias. Hyperkalemia has been reported in 1.3% (serum potassium greater than 6.0 mEq/mL) to 10% (greater than 5.3 mEq/mL) of patients. Hyperkalemia secondary to beta-adrenergic receptor blockade can occur in 1% to 5% of patients and is more likely to occur in non-cardio-selective beta-blockers versus cardio-selective beta-blockers. This case report describes hyperkalemia in a 72-year-old female with diabetes and underlying chronic renal failure receiving metoprolol. Chronically, potassium balance is maintained by the kidney. In acute situations, such as a larger than normal potassium load, both the kidney and the body's cells react to maintain normal potassium levels. Generally, hyperkalemia occurs secondary to 3 mechanisms: excessive potassium intake, disturbed cellular uptake of potassium, or impaired renal excretion of potassium. Beta-blockers, when used in patients with comorbidities such as renal dysfunction or insulin insufficiency, can potentially cause hyperkalemia. As demonstrated in this case report, hyperkalemia can occur in patients treated with cardio-selective beta-blockers with concurrent risk factors. Health care professionals need to be aware of this potentially life-threatening event to effectively prevent occurrences of beta-blocker-induced hyperkalemia.