When is calcium gluconate administered for hyperkalemia?

When to Administer Calcium Gluconate for Hyperkalemia

Calcium gluconate should be administered immediately when hyperkalemia causes ECG changes (peaked T waves, widened QRS, prolonged PR interval, flattened P waves) OR when potassium is ≥6.5 mEq/L, regardless of ECG findings. 1, 2

Indications for Immediate Calcium Administration

Absolute Indications (Administer Without Delay)

• Any ECG changes attributable to hyperkalemia, including peaked T waves, flattened P waves, prolonged PR interval, widened QRS complexes, or cardiac arrhythmias 1, 2, 3
• Severe hyperkalemia (K+ ≥6.5 mEq/L), even without ECG changes 1, 2
• Hemodynamic instability (hypotension, bradycardia, circulatory shock) in the setting of hyperkalemia 4

Key Clinical Algorithm

1. Obtain ECG immediately when hyperkalemia is suspected—do not wait for repeat potassium levels if ECG changes are present 1
2. Administer calcium if ANY of the following are present:
   • ECG changes consistent with hyperkalemia 1, 2
   • K+ ≥6.5 mEq/L 1, 2
   • Cardiac arrhythmias or hemodynamic compromise 4, 5

Dosing and Administration

• Calcium gluconate 10%: 15-30 mL IV over 2-5 minutes (preferred for peripheral access) 1, 2
• Calcium chloride 10%: 5-10 mL IV over 2-5 minutes (alternative, provides more rapid ionized calcium increase but requires central access due to tissue injury risk) 1, 2
• Onset of action: 1-3 minutes 1, 2
• Duration of effect: 30-60 minutes only 1, 2

Critical Monitoring and Repeat Dosing

• Monitor ECG continuously during and for 5-10 minutes after calcium administration 1
• If no ECG improvement within 5-10 minutes, repeat the dose (another 15-30 mL calcium gluconate) 1, 2
• Calcium does NOT lower potassium levels—it only temporarily stabilizes cardiac membranes 1, 2, 3

When NOT to Give Calcium

• Moderate hyperkalemia (K+ 6.0-6.4 mEq/L) WITHOUT ECG changes—proceed directly to potassium-lowering therapies (insulin/glucose, albuterol) 1, 2
• Mild hyperkalemia (K+ 5.0-5.9 mEq/L) WITHOUT ECG changes—calcium is not indicated 1, 2
• Elevated phosphate levels—use calcium cautiously as it increases risk of calcium-phosphate precipitation 1
• Malignant hyperthermia with hyperkalemia—calcium should only be used in extremis due to myoplasmic calcium overload risk 1

Common Pitfalls to Avoid

• Never delay calcium administration while waiting for repeat potassium levels if ECG changes are present—ECG changes indicate urgent need regardless of exact potassium value 1
• Never rely on calcium alone—simultaneously initiate potassium-lowering therapies (insulin/glucose, albuterol, diuretics) as calcium provides only 30-60 minutes of protection 1, 2
• Never administer calcium through the same IV line as sodium bicarbonate—precipitation will occur 1
• Do not assume absence of ECG changes means safety—ECG findings can be highly variable and less sensitive than laboratory values 1

Complete Treatment Sequence After Calcium

After stabilizing cardiac membranes with calcium, immediately initiate:

1. Shift potassium into cells (onset 15-30 minutes): 1, 2

   • Insulin 10 units IV + 25g glucose (50 mL D50W)
   • Nebulized albuterol 10-20 mg over 15 minutes
   • Sodium bicarbonate 50 mEq IV ONLY if metabolic acidosis present

2. Remove potassium from body: 1, 2

   • Loop diuretics (furosemide 40-80 mg IV) if adequate renal function
   • Newer potassium binders (patiromer or sodium zirconium cyclosilicate)
   • Hemodialysis for severe/refractory cases or renal failure