Which EKG change is characteristic of hyperkalemia?

Peaked or narrow T waves are a hallmark indicator of hyperkalemia on an electrocardiogram (EKG). As the potassium levels in the blood increase, the T waves become more pronounced and can take on a peaked appearance. This change occurs due to the effect of elevated potassium on cardiac myocytes, which alters the repolarization process.

In normal physiology, the T wave represents the repolarization of the ventricles. When there is an excess of potassium, the cardiac cells become more depolarized, leading to this distinctive T wave morphology. Recognizing peaked T waves is critical for paramedics and healthcare providers, as it signals a potentially serious electrolyte imbalance that may require immediate intervention to prevent life-threatening arrhythmias or cardiac arrest.