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Potassium is a HIGH-ALERT medication. Rapid IV administration can cause cardiac arrest. Never give IV bolus. Use infusion pump. Cardiac monitoring required for severe hypokalemia.
Calculate potassium replacement dosing for hypokalemia
Normal: 3.5-5.0 mEq/L
| Serum K+ (mEq/L) | Severity | IV Dose | PO Dose | Monitoring |
|---|---|---|---|---|
| <2.0 | Severe | 40 mEq | 80 mEq | ICU, continuous cardiac monitor, recheck q2-4h |
| 2.0-2.4 | Moderate-Severe | 40 mEq | 40 mEq | Cardiac monitor recommended, recheck q4h |
| 2.5-2.9 | Moderate | 20 mEq | 40 mEq | Recheck in 6 hours |
| 3.0-3.4 | Mild | 10 mEq | 40 mEq (preferred) | Recheck in 12-24 hours |
| 3.5-3.9 | Low-Normal | Not needed | 20 mEq | Recheck in 24 hours |
| 4.0-5.0 | Normal | None | None | Routine |
| Access | Max Rate | Max Concentration | Notes |
|---|---|---|---|
| Peripheral IV | 10 mEq/hr | 40 mEq/L | Standard for most patients |
| Central Line | 20 mEq/hr | 80 mEq/L | For severe hypokalemia |
| Emergency (Central) | Up to 40 mEq/hr | 80 mEq/L | Life-threatening arrhythmia only, ICU with continuous monitoring |
Check magnesium! Hypomagnesemia prevents potassium correction because magnesium is required for the Na-K-ATPase pump. Always check and replace magnesium when treating hypokalemia. Also assess for ongoing losses (diarrhea, NG suction, diuretics).
KCl (potassium chloride) is most common and corrects both K+ and Cl-. K-Phos (potassium phosphate) is used when both K+ and phosphate are low. K-Acetate is used in severe metabolic acidosis. KCl is preferred unless there's a specific indication for alternatives.
In life-threatening situations (severe arrhythmias), rates up to 40 mEq/hr via central line may be used in ICU with continuous cardiac monitoring. However, this carries significant risk and should only be done by experienced clinicians.
Roughly, 40 mEq PO KCl raises serum K+ by 0.5-1.0 mEq/L. However, this varies based on absorption, renal function, and ongoing losses. IV replacement is more predictable: 10-20 mEq typically raises K+ by 0.1-0.2 mEq/L.
Use PO whenever possible as it's safer and better tolerated long-term. Use IV for: K+ <2.5 mEq/L, symptomatic hypokalemia, NPO status, severe GI losses, or when rapid correction is needed. Switch to PO once K+ >3.0 mEq/L and patient tolerating PO.