Recognize
- Mild 3.0–3.5 · Moderate 2.5–3.0 · Severe < 2.5 mEq/L
- Symptoms: weakness, cramps, ileus, palpitations, polyuria
- EKG: flat / inverted T, U waves, ST depression, prolonged QT, PVCs, torsades
- Causes: GI loss (vomiting/diarrhea), diuretics, alkalosis, insulin/β-agonists, ↓ Mg, RTA, hyperaldo
Replacement — IV
- KCl IV 10 mEq/h via peripheral (max 20 mEq/h via central with telemetry)
- Each 10 mEq IV ≈ ↑ serum K by ~0.1 mEq/L
- Max concentration: 10 mEq/100 mL peripheral · 20 mEq/100 mL central
- Burning at IV site common — slow rate or dilute
- Telemetry for rates > 10 mEq/h or K < 2.5
Replacement — PO
- KCl PO 40–100 mEq divided (e.g. 20–40 mEq q4–6h)
- Preferred when patient tolerates PO and not severe
- Each 10 mEq PO ≈ ↑ K by ~0.1 mEq/L
Co-repletion
- Replace Mg — refractory hypokalemia until Mg corrected
- MgSO₄ 2 g IV over 1 h if Mg < 2.0
- Recheck K 1–2 h after IV repletion · 2–4 h after PO
Disposition
- Admit: K < 2.5, EKG changes, arrhythmia, ongoing losses, symptomatic
- Discharge: mild asymptomatic with PO replacement + outpatient recheck