Potassium Imbalance: Hypokalemia vs Hyperkalemia — ECG, Symptoms, Interventions
A potassium of 3.0 and a potassium of 6.5 both trigger lethal dysrhythmias, but the ECG patterns, symptoms, and emergency interventions are mirror opposites. Picking the wrong correction on the NCLEX means choosing the action that kills the patient.
Comparison
- Loop / thiazide diuretics
- Vomiting, NG suction
- Alkalosis; insulin administration
- Renal failure
- K⁺-sparing diuretics (spironolactone)
- Crush injury; acidosis; transfusion
- Skeletal weakness, leg cramps, fatigue
- Hyporeflexia; ↓ GI motility, ileus
- Muscle twitching, paresthesias
- Ascending flaccid paralysis; diarrhea
- Serum K⁺ < 3.5; flat/inverted T waves
- ★Prominent U waves; ST depression
- ★Tall peaked T waves (early)
- Serum K⁺ >5.0; widened QRS, loss of P
- Continuous telemetry
- Check Mg²⁺ (blocks K⁺ fix)
- KCl is a vesicant — check IV site
- Continuous telemetry
- Recheck K⁺ 1 hr post-treatment
- Watch rebound hypokalemia after insulin
- ★IV KCl ≤10 mEq/hr peripheral; never IV push
- Always use an infusion pump
- ★Calcium gluconate IV first (stabilizes heart)
- Insulin+D50, bicarb; Kayexalate, dialysis
- Increase K⁺ foods: bananas, potatoes, spinach
- Restrict K⁺-rich foods; read labels
- Avoid salt substitutes (contain KCl)
- PVCs, V-tach, V-fib
- Potentiates digoxin toxicity
- Bradycardia, heart block, asystole
- Risk spikes when K⁺ > 6.5
- Lethal dysrhythmias; paralytic ileus
- Sine wave → asystole; cardiac arrest
Hypokalemia (< 3.5 mEq/L)
- Loop / thiazide diuretics
- Vomiting, NG suction
- Alkalosis; insulin administration
Hyperkalemia (> 5.0 mEq/L)
- Renal failure
- K⁺-sparing diuretics (spironolactone)
- Crush injury; acidosis; transfusion
Hypokalemia (< 3.5 mEq/L)
- Skeletal weakness, leg cramps, fatigue
- Hyporeflexia; ↓ GI motility, ileus
Hyperkalemia (> 5.0 mEq/L)
- Muscle twitching, paresthesias
- Ascending flaccid paralysis; diarrhea
Hypokalemia (< 3.5 mEq/L)
- Serum K⁺ < 3.5; flat/inverted T waves
- ★Prominent U waves; ST depression
Hyperkalemia (> 5.0 mEq/L)
- ★Tall peaked T waves (early)
- Serum K⁺ >5.0; widened QRS, loss of P
Hypokalemia (< 3.5 mEq/L)
- Continuous telemetry
- Check Mg²⁺ (blocks K⁺ fix)
- KCl is a vesicant — check IV site
Hyperkalemia (> 5.0 mEq/L)
- Continuous telemetry
- Recheck K⁺ 1 hr post-treatment
- Watch rebound hypokalemia after insulin
Hypokalemia (< 3.5 mEq/L)
- ★IV KCl ≤10 mEq/hr peripheral; never IV push
- Always use an infusion pump
Hyperkalemia (> 5.0 mEq/L)
- ★Calcium gluconate IV first (stabilizes heart)
- Insulin+D50, bicarb; Kayexalate, dialysis
Hypokalemia (< 3.5 mEq/L)
- Increase K⁺ foods: bananas, potatoes, spinach
Hyperkalemia (> 5.0 mEq/L)
- Restrict K⁺-rich foods; read labels
- Avoid salt substitutes (contain KCl)
Hypokalemia (< 3.5 mEq/L)
- PVCs, V-tach, V-fib
- Potentiates digoxin toxicity
Hyperkalemia (> 5.0 mEq/L)
- Bradycardia, heart block, asystole
- Risk spikes when K⁺ > 6.5
Hypokalemia (< 3.5 mEq/L)
- Lethal dysrhythmias; paralytic ileus
Hyperkalemia (> 5.0 mEq/L)
- Sine wave → asystole; cardiac arrest
★ marks the fact that sets a column apart.
Clinical Pearl
Flat T = low K⁺; peaked T = high K⁺ — the T wave mirrors the potassium level.
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