What should be done if a patient's potassium level exceeds 6.5 mEq/L while on an ACE inhibitor?

When a patient's potassium level exceeds 6.5 mEq/L, particularly in the context of being on an ACE inhibitor, immediate action is required due to the significant risk of life-threatening hyperkalemia. This condition can lead to severe cardiac complications, including arrhythmias, and necessitates prompt intervention.

Ceasing the ACE inhibitor is critical as it can further exacerbate potassium retention. Additionally, sending the patient to the emergency department (ED) is warranted to ensure they receive appropriate monitoring and treatment, which may include the administration of calcium gluconate or sodium bicarbonate to stabilize cardiac function, as well as measures to lower serum potassium levels.

Monitoring potassium levels closely or continuing the ACE inhibitor are not advisable in this situation because the high potassium level already indicates a physiological disturbance that needs intervention beyond observation. Reducing the dose of the ACE inhibitor may not be sufficient in cases of significant hyperkalemia; thus, the most appropriate action would be to stop the medication entirely and manage the electrolyte imbalance urgently.