AEMCA Practice Exam

The most concerning symptom of severe hyperkalemia is the suppression of electrical activity in the heart. Elevated potassium levels in the blood can significantly affect the heart's rhythm and electrical conduction system. As potassium is crucial for maintaining the depolarization and repolarization phases of cardiac action potentials, excessive potassium can lead to life-threatening cardiac arrhythmias, including both bradycardia (slow heart rate) and potentially fatal rhythms such as ventricular fibrillation or asystole. In contrast, while high blood pressure may occur in specific circumstances, it is not directly linked to the immediate dangers associated with hyperkalemia. Increased urination is generally not a prominent symptom of severe hyperkalemia; instead, it may indicate diuresis or underlying kidney function. Nausea and vomiting can occur with many medical conditions, including hyperkalemia, but they are not as critical as the risk of cardiac disturbances. Thus, the suppression of electrical activity in the heart represents the most severe and urgent concern when evaluating the implications of hyperkalemia.