✨ Featured Lessons · Lesson 2 of 8 · 60 sec
Why Potassium Is the Deadliest Electrolyte
🍌 Too little and the heart quivers. Too much and it stops. Potassium is lethal at both ends of a narrow normal range, and it is one of the most tested numbers on the exam.
💡 Key idea
Peaked T means high: calcium, insulin and dextrose, remove it. U waves mean low: replace slowly, never push.
🧠 Why it matters
Normal is 3.5 to 5.0. HIGH potassium gives tall peaked T waves and a widening QRS; treat the heart first with calcium gluconate, then shift potassium into cells with insulin and dextrose, then remove it with binders or dialysis. LOW potassium gives flat T waves and U waves, weakness and dangerous digoxin sensitivity; replace it by mouth or by pump at no more than about 10 mEq per hour peripherally. Never, under any circumstances, IV push.
🏥 In the real world
💉 A nurse once received an order for 'KCl 20 mEq IV' and drew it into a syringe. The pharmacist's phone call saved a life. Concentrated potassium has been removed from most units for exactly this reason, and the exam will keep asking until every nurse knows why.
📌 Takeaways
- 3.5 to 5.0; both directions cause arrhythmias
- High: calcium gluconate protects, insulin and dextrose shift, dialysis removes
- Low: watch digoxin clients; never IV push
✅ Test yourself
Which ECG change signals hyperkalemia?
- Tall peaked T waves
- A shortened PR interval
- ST elevation
- Flattened T waves with U waves
Answer: A · Tall peaked T waves
Peaked T waves are the earliest ECG sign of high potassium; flat T waves and U waves point to low potassium.
A nurse receives an order for potassium chloride IV push. What is the correct action?
- Give it over 5 minutes
- Dilute it in 10 mL and push slowly
- Question the order
- Give it only through a central line
Answer: C · Question the order
Potassium is never given IV push, through any line or at any speed: it can cause cardiac arrest. It is always diluted and infused by pump at a controlled rate.
NCLEX-style questions, XP and streaks in the app. No sign-up needed.
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- 1The 3-Second Rule for 'Which Client First?'
- 2Why Potassium Is the Deadliest Electrolyte
- 3My Chicken Hez TB: Isolation in 60 Seconds
- 4Delegation Cheat Code: Never Delegate What You EAT
- 5The Lab Values You Must Recite in Your Sleep
- 6Late Decels: Four Moves in Sixty Seconds
- 7Insulin Peaks in One Picture
- 8Never Push, Never Crush, Never Clamp