How do I replete calcium intravenously (IV)?

Intravenous Calcium Repletion Protocol

For intravenous calcium repletion, use calcium gluconate 10% at a dose of 1-2 g for mild hypocalcemia and 2-4 g for moderate to severe hypocalcemia, administered over 30-60 minutes for non-emergent cases and as a slow IV push over 5-10 minutes for cardiac arrest situations. 1, 2

Calcium Salt Selection

• Calcium gluconate (preferred for peripheral IV administration)

  • Contains 9.3 mg (0.465 mEq) of elemental calcium per 100 mg
  • Standard dose: 1-2 g for mild hypocalcemia, 2-4 g for moderate to severe hypocalcemia
  • Less irritating to veins, safer for peripheral administration

• Calcium chloride (preferred for critically ill patients)

  • More concentrated: 10% calcium chloride (0.2 mL/kg) provides faster increase in ionized calcium
  • Dose: 20 mg/kg (0.2 mL/kg for 10% CaCl₂)
  • Requires central venous access due to high risk of tissue necrosis if extravasation occurs
  • Dose equivalence: 10 mL of 10% calcium gluconate (2.2 mmol calcium) ≈ 4.4 mL of 7.35% calcium chloride 3

Administration Protocol

For Non-Emergency Hypocalcemia:

1. Dilution:

   • Dilute calcium gluconate in 5% dextrose or normal saline to a concentration of 10-50 mg/mL 2
   • For continuous infusion: dilute to 5.8-10 mg/mL 2

2. Administration rate:

   • Infuse over 30-60 minutes for non-emergent cases 1
   • Do not exceed 200 mg/minute in adults or 100 mg/minute in pediatric patients 2

3. Monitoring:

   • Monitor heart rate during administration
   • Stop injection if symptomatic bradycardia occurs
   • Monitor serum calcium every 4-6 hours during intermittent infusions and every 1-4 hours during continuous infusion 2

For Emergency/Severe Hypocalcemia:

1. Loading dose:

   • 10-20 mL of 10% calcium gluconate (1-2 g) in 50-100 mL of 5% dextrose IV over 10 minutes with ECG monitoring 3
   • Can be repeated until the patient is asymptomatic

2. Maintenance infusion:

   • Dilute 100 mL of 10% calcium gluconate (10 vials) in 1 L of normal saline or 5% dextrose
   • Infuse at 50-100 mL/h 3
   • Titrate rate to achieve normocalcemia

3. For cardiac arrest situations:

   • Give by slow IV push for cardiac arrest 1
   • Recommended only for documented hypocalcemia, hyperkalemia, hypermagnesemia, or calcium channel blocker toxicity 1

Special Considerations

• Vascular access:

  • Administration through a central venous catheter is preferred for calcium chloride
  • Ensure secure peripheral IV for calcium gluconate to avoid calcinosis cutis and tissue necrosis 2

• Incompatibilities:

  • Do not mix with bicarbonate or phosphate-containing fluids (precipitation may occur)
  • Do not mix with ceftriaxone (risk of precipitate formation)
  • Do not mix with minocycline injection 2
  • Do not mix with vasoactive amines 1

• Efficacy:

  • 1-2 g of IV calcium gluconate is effective in normalizing ionized calcium in 79% of patients with mild hypocalcemia
  • 2-4 g is effective in only 38% of patients with moderate to severe hypocalcemia 4
  • Individual response to calcium therapy is highly variable 4

• Maximum single dose:

  • Do not administer more than 500 mg elemental calcium at one time 5

Specific Clinical Scenarios

• For calcium channel blocker toxicity:

  • Administer 0.3 mEq/kg of calcium (0.6 mL/kg of 10% calcium gluconate) IV over 5-10 minutes
  • Follow with infusion of 0.3 mEq/kg per hour
  • Titrate to hemodynamic response 1
  • Monitor ionized calcium levels to avoid hypercalcemia 1

• For hyperkalemia or hypermagnesemia:

  • Calcium gluconate (10%) 15-30 mL IV over 2-5 minutes during cardiac arrest 1

Pitfalls and Caveats

• Calcium chloride administration results in a more rapid increase in ionized calcium than calcium gluconate but carries higher risk of tissue damage if extravasated
• Extravasation through a peripheral IV line may cause severe skin and soft tissue injury
• Frequent monitoring of ionized calcium is essential to avoid hypercalcemia
• Response to calcium therapy is highly variable between patients, requiring individualized dose titration
• For patients with renal impairment, start at the lowest recommended dose and monitor calcium levels more frequently 2