What is the recommended dose of calcium gluconate (Ca gluconate) for a patient with severe hyperkalemia and cardiac symptoms?

Calcium Gluconate Dosing for Hyperkalemia

For severe hyperkalemia with cardiac symptoms, administer 15-30 mL of 10% calcium gluconate IV over 2-5 minutes, with continuous ECG monitoring and readiness to repeat the dose in 5-10 minutes if no improvement occurs. 1, 2, 3

Standard Adult Dosing

• Administer 1.5-3 grams (15-30 mL of 10% solution) IV over 2-5 minutes for patients with severe hyperkalemia and ECG changes (peaked T waves, widened QRS, prolonged PR interval, or arrhythmias). 1, 2, 3

• The FDA-approved dosing range is 1,000-2,000 mg (10-20 mL of 10% solution) for acute symptomatic hypocalcemia, but emergency guidelines for hyperkalemia recommend up to 3,000 mg (30 mL). 4

• Do not exceed an infusion rate of 200 mg/minute in adults to avoid bradycardia and other cardiac complications. 4

Pediatric Dosing

• Administer 100-200 mg/kg/dose via slow IV infusion with continuous ECG monitoring for pediatric patients with hyperkalemia and cardiac symptoms. 1, 3

• Alternatively, use 20 mg/kg (0.2 mL/kg of 10% calcium chloride) for pediatric patients, though calcium gluconate is preferred for peripheral IV access due to lower tissue injury risk. 2, 3

• Do not exceed an infusion rate of 100 mg/minute in pediatric patients, including neonates. 4

Repeat Dosing Protocol

• Monitor the ECG continuously during and for 5-10 minutes after the initial calcium dose. 2, 3

• If no ECG improvement occurs within 5-10 minutes, administer a second dose of 15-30 mL of 10% calcium gluconate IV over 2-5 minutes. 2, 3

• The onset of cardioprotective effects occurs within 1-3 minutes, but the duration is only 30-60 minutes, so concurrent potassium-lowering therapies must be initiated immediately. 2, 3

Critical Administration Details

Route and Preparation

• Use calcium gluconate (not calcium chloride) for peripheral IV access to minimize tissue necrosis risk if extravasation occurs. 3

• Dilute calcium gluconate to a concentration of 10-50 mg/mL in 5% dextrose or normal saline for bolus administration. 4

• Administer via a secure IV line to avoid calcinosis cutis and tissue necrosis. 4

Drug Incompatibilities

• Never administer calcium through the same IV line as sodium bicarbonate—precipitation will occur. 2, 3

• Do not mix with ceftriaxone (contraindicated in neonates ≤28 days), fluids containing bicarbonate or phosphate, or minocycline. 4

Monitoring Requirements

• Continuous cardiac monitoring is mandatory during calcium administration, with particular attention to heart rate—stop injection if symptomatic bradycardia occurs. 2, 3, 4

• Measure serum potassium every 2-4 hours after initial treatment to assess response and guide repeat dosing. 2

Mechanism and Limitations

• Calcium does NOT lower serum potassium—it only temporarily stabilizes cardiac membranes by counteracting the depolarizing effects of hyperkalemia. 2, 3

• The cardioprotective effect lasts only 30-60 minutes, so failure to initiate concurrent potassium-lowering therapies (insulin/glucose, albuterol, dialysis) will result in recurrent life-threatening arrhythmias. 2, 3

• Recent research suggests calcium gluconate is effective primarily for main rhythm disorders (e.g., bradycardia, AV block) but may not improve non-rhythm ECG changes (e.g., peaked T waves, QRS widening) in all patients. 5

Special Populations

Renal Impairment

• Initiate calcium gluconate at the lowest recommended dose and monitor serum calcium levels every 4 hours in patients with renal impairment. 4

Elevated Phosphate Levels

• Use calcium cautiously in patients with high phosphate levels (e.g., tumor lysis syndrome, rhabdomyolysis) as it increases the risk of calcium-phosphate precipitation in tissues. 2, 3

Malignant Hyperthermia

• In patients with malignant hyperthermia and hyperkalemia, calcium should only be used in extremis as it may contribute to calcium overload of the myoplasm. 2

Common Pitfalls to Avoid

• Do not delay calcium administration while waiting for repeat potassium levels if ECG changes are present—ECG changes indicate urgent need regardless of the exact potassium value. 2, 3

• Do not rely on calcium alone—it is a temporizing measure only, and concurrent potassium-lowering therapies must be initiated immediately. 2, 3

• Do not give insulin without glucose—hypoglycemia can be life-threatening and may occur even in hyperglycemic patients. 2

• Remember that calcium, insulin, and beta-agonists do not remove potassium from the body—they only temporize until definitive removal via dialysis, diuretics, or potassium binders. 2

Concurrent Therapies (Must Be Initiated Simultaneously)

While calcium stabilizes the cardiac membrane, immediately initiate the following to actually lower potassium:

• Insulin 10 units regular IV + 25g dextrose (50 mL D50W) over 15-30 minutes (onset 15-30 minutes, duration 4-6 hours). 2

• Nebulized albuterol 10-20 mg in 4 mL as adjunctive therapy (onset 15-30 minutes, duration 2-4 hours). 2

• Sodium bicarbonate 50 mEq IV over 5 minutes ONLY if metabolic acidosis is present (pH <7.35, bicarbonate <22 mEq/L). 2

• Loop diuretics (furosemide 40-80 mg IV) if adequate renal function exists. 2

• Hemodialysis for severe cases unresponsive to medical management, oliguria, or end-stage renal disease—this is the most effective method for potassium removal. 2