Calcium Gluconate Dosing for Hypocalcemia
For a patient with total calcium 7.7 mg/dL and ionized calcium 1.08 mmol/L, initiate a continuous IV calcium gluconate infusion at 1-2 mg elemental calcium per kilogram body weight per hour, targeting an ionized calcium in the normal range of 1.15-1.36 mmol/L. 1
Assessment of Calcium Status
Your patient's values indicate true hypocalcemia requiring treatment:
- Total calcium 7.7 mg/dL is below the normal range of 8.6-10.3 mg/dL 2
- Ionized calcium 1.08 mmol/L is below the normal range of 1.16-1.32 mmol/L 2
- Both values are abnormal, confirming the need for intervention 2
Acute IV Calcium Replacement
Continuous infusion approach (preferred for sustained correction):
- Calculate dose: 1-2 mg elemental calcium/kg/hour 1
- Remember: Each 10 mL ampule of 10% calcium gluconate contains 90 mg elemental calcium 1
- For a 70 kg patient: 70-140 mg elemental calcium/hour = approximately 8-16 mL of 10% calcium gluconate per hour 1
- Adjust infusion rate to maintain ionized calcium 1.15-1.36 mmol/L 1
Alternative bolus approach (for symptomatic patients):
- Administer 50-100 mg/kg IV calcium gluconate slowly with continuous ECG monitoring 2
- For a 70 kg patient: 3,500-7,000 mg calcium gluconate = 35-70 mL of 10% solution 2
- Give slowly over 10-20 minutes to avoid cardiac complications 2
Critical Monitoring Requirements
Ionized calcium monitoring frequency:
- Measure every 4-6 hours for the first 48-72 hours 1
- Then twice daily until stable 1
- Continuous ECG monitoring during initial infusion 2
Important caveat: If phosphate levels are elevated, exercise caution as increased calcium administration may precipitate calcium-phosphate deposition in tissues 2. Check phosphate levels before aggressive calcium replacement 2.
Transition to Oral Therapy
Once ionized calcium normalizes and remains stable:
- Gradually reduce the IV infusion 1
- When oral intake is possible, start calcium carbonate 1-2 g three times daily (providing 1,200-2,400 mg elemental calcium daily) 1, 2
- Add calcitriol up to 2 mcg/day as needed to maintain normal ionized calcium 1
Special Considerations
Calcium chloride alternative:
- Contains 270 mg elemental calcium per 10 mL of 10% solution (versus 90 mg in calcium gluconate) 2
- May be preferable in patients with abnormal liver function 2
- Provides more rapid correction but requires central venous access due to tissue irritation 2
Long-term management targets: