⚡ Hyperkalemia: ECG Changes, Emergency Management & USMLE Pearls
Hyperkalemia is not only life-threatening—it’s test-lovable.
Whether it’s due to renal dysfunction, medications like ACE inhibitors, or rhabdomyolysis, recognizing elevated potassium levels and their effects on the heart is a high-yield skill that pops up repeatedly on the USMLE.
In this blog, we’ll break down:
Key causes of hyperkalemia
Classic ECG changes you’ll see on exams
Emergency treatment protocols
Clinical pearls with KOTC flavor
🧪 What is Hyperkalemia?
Definition:
Hyperkalemia = Serum K⁺ > 5.0 mEq/L
Common Causes:
Renal failure
ACE inhibitors / ARBs
Spironolactone, NSAIDs
Cell lysis (e.g., rhabdomyolysis, tumor lysis syndrome)
Acidosis (K⁺ shifts out of cells)
💡 USMLE Pearl: Peaked T waves are the earliest sign. As potassium climbs, QRS widens dangerously.
📊 ECG Changes in Hyperkalemia
| Serum K⁺ Level | ECG Finding |
|---|---|
| 5.5–6.5 mEq/L | Peaked T waves |
| 6.5–7.5 mEq/L | PR prolongation, QRS widening |
| >7.5 mEq/L | Sine wave pattern → asystole risk |
💡 USMLE Pearl: Peaked T waves are the earliest sign. As potassium climbs, QRS widens dangerously.
🧑⚕️ Emergency Management of Hyperkalemia
| Goal | Treatment | Mechanism |
|---|---|---|
| Stabilize cardiac membrane | IV calcium gluconate | Raises threshold potential |
| Shift K⁺ into cells | Insulin + glucose, Beta-agonists, Sodium bicarbonate | Drives K⁺ intracellular |
| Eliminate K⁺ | Furosemide, Kayexalate, Hemodialysis | Removes potassium from body |
🔥 USMLE Tip: Calcium gluconate is always first in symptomatic or ECG-positive hyperkalemia.
🧠 Clinical Signs
Muscle weakness
Flaccid paralysis
Cardiac arrhythmias
Nausea, paresthesias
Often asymptomatic until very high
🔍 USMLE-Style Scenario
A 63-year-old man with CKD presents with palpitations. ECG shows peaked T waves and a wide QRS complex. What is the first step in management?
✅ Answer: IV Calcium gluconate to stabilize cardiac membranes.
🎓 Call to Action
Want to master high-risk, high-yield cases like hyperkalemia?
💥 Join over 100,000 students using KOTC’s gamified platform with:
Daily USMLE-style questions
Adaptive Q-Bank
Multiplayer + Curve Coins
ECG + electrolyte visuals
Clinical crash course vignettes
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