What are the hallmark ECG changes of hyperkalemia and the initial urgent treatment steps?

• A. Peaked T waves progressing to widened QRS and sine wave; treat with IV calcium gluconate, then insulin with glucose or albuterol, and remove potassium
• B. Normal ECG
• C. Inverted T waves; give bicarbonate
• D. ST depressions; administer diuretics

Answer: (A)

Hyperkalemia directly affects cardiac conduction, so the ECG changes reflect the progression of electrical instability. The earliest hallmark is tall, peaked T waves; as potassium rises, the PR interval may lengthen and the QRS complex widens, eventually merging into a sine-wave pattern. This progression signals increasing risk of dangerous arrhythmias, so treatment must act quickly to stabilize the heart and lower the potassium load.

The best initial urgent steps are to stabilize the myocardium with intravenous calcium (calcium gluconate), which protects cardiac cells from the high potassium without changing its level. After the heart is stabilized, shift potassium into cells using insulin given with glucose or a beta-agonist such as albuterol. Finally, begin removing potassium from the body, using strategies like diuretics or potassium-binding agents, and escalate to dialysis if needed based on renal function and severity.

Other options don’t match the classic ECG progression or the immediate stabilization plan. Normal ECG isn’t typical in hyperkalemia with dangerous potassium levels, inverted T waves and bicarbonate don’t reflect the urgent stabilization and intracellular shift sequence, and relying on diuretics alone doesn’t address the immediate risk to the heart.