EKG

EKG changes by electrolyte

EKG

EKG changes by electrolyte

Hyperkalemia, hypokalemia, hypocalcemia, hypercalcemia — recognize and treat fast.

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◆Potassium

•Hyperkalemia (rising): peaked T waves → PR prolongation, P-wave flattening → wide QRS → sine-wave → asystole/VF
•Hypokalemia: U waves, T-wave flattening, ST depression, prolonged QT — predisposes to torsades

◆Calcium

•Hypocalcemia: prolonged QT (specifically prolonged ST segment) — risk of torsades
•Hypercalcemia: SHORT QT, Osborn (J) waves with severe hypercalcemia

◆Treatment priorities

•Hyperkalemia with EKG changes → calcium gluconate IV (stabilizes membrane) FIRST → insulin + glucose, β-agonist (shift K into cells) → kayexalate / dialysis (remove K)
•Hypokalemia → replace K AND magnesium (Mg deficit prevents K replenishment)
•Hypocalcemia symptomatic → IV calcium gluconate
•Hypercalcemia → IV normal saline; calcitonin for fast effect; bisphosphonate for sustained

Electrolyte EKG signature

Finding	Likely electrolyte
Peaked T waves	Hyperkalemia
U waves, ↓K rhythm	Hypokalemia
Prolonged QT (long ST)	Hypocalcemia
Short QT, Osborn waves	Hypercalcemia
Sine wave QRS	Severe (>7) hyperkalemia

High-yield pearls

◆Calcium gluconate stabilizes the myocyte but does NOT lower K — still need to shift + remove
◆Hypokalemia is resistant to correction without simultaneous magnesium repletion
◆Digoxin toxicity mimics hyperkalemia EKG findings + 'scooped' ST depression

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