Calcium Gluconate Dosing for Hypocalcemia
For a 94 kg patient with ionized calcium of 0.74 mmol/L, you should NOT use calcium gluconate—instead, administer calcium chloride at a dose of 2000 mg (20 mL of 10% solution) immediately, as calcium chloride provides three times more elemental calcium than calcium gluconate and is the preferred agent for correcting hypocalcemia in critical situations. 1
Why Calcium Chloride Over Calcium Gluconate
- Calcium chloride is superior because 10 mL of 10% calcium chloride contains 270 mg of elemental calcium, while the same volume of 10% calcium gluconate contains only 90 mg of elemental calcium 2
- In critical hypocalcemia (ionized Ca <0.9 mmol/L), calcium chloride is the recommended agent for emergency correction 2, 1
- Your patient's ionized calcium of 0.74 mmol/L is significantly below the normal range of 1.1-1.3 mmol/L and below the critical threshold of 0.9 mmol/L 2
Specific Dosing Protocol
Initial bolus:
- Administer 2000 mg calcium chloride (20 mL of 10% solution) for this 94 kg adult patient 1
- This can be given as a slow IV push or diluted infusion
If using calcium gluconate despite the recommendation against it:
- You would need approximately 6 ampules (60 mL of 10% calcium gluconate) to provide equivalent elemental calcium to one dose of calcium chloride 2
- Each 10 mL ampule of 10% calcium gluconate contains only 90 mg elemental calcium 2
Maintenance Therapy
After initial correction:
- Start a maintenance infusion at 20-40 mg/kg/h of elemental calcium if hypocalcemia persists 1
- For this 94 kg patient, this translates to 1880-3760 mg/hour of elemental calcium
- Monitor ionized calcium every 4-6 hours initially, then twice daily until stable 2
Critical Clinical Context
Your patient is at high risk because:
- Ionized calcium below 0.8 mmol/L is associated with cardiac dysrhythmias 2
- At 0.74 mmol/L, this patient has severe hypocalcemia affecting coagulation, platelet function, cardiac contractility, and vascular resistance 2
- Hypocalcemia at this level is associated with increased mortality in critically ill patients 2, 3
Important Caveats
- Calcium chloride may be preferable in liver dysfunction, as calcium gluconate requires hepatic metabolism to release ionized calcium 2
- Administer through a central line when possible, especially if repeated dosing is needed 1
- Do not rely on total calcium levels—only ionized calcium accurately reflects the biologically active form 4, 5
- Very high infusion rates may be required to restore normal ionized calcium in critically ill patients, and calcium therapy alone may not be sufficient in severe low-flow states 4
- Monitor for overcorrection—maintain ionized calcium in the normal range of 1.1-1.3 mmol/L, not higher 2