What is the recommended perfusion dose of calcium gluconate (Ca gluconate) for treating severe hypocalcemia?

Calcium Gluconate Infusion for Severe Hypocalcemia

For severe hypocalcemia (ionized calcium <0.9 mmol/L or corrected total calcium <7.2 mg/dL), initiate a continuous calcium gluconate infusion at 1-2 mg elemental calcium per kilogram body weight per hour, adjusted to maintain ionized calcium in the normal range (1.15-1.36 mmol/L). 1

Initial Bolus Dosing

• Administer 10-20 mL of 10% calcium gluconate (equivalent to 1-2 grams) diluted in 50-100 mL of 5% dextrose or normal saline intravenously over 10 minutes with continuous ECG monitoring 2
• This bolus can be repeated until the patient becomes asymptomatic 2
• Each 10 mL ampule of 10% calcium gluconate contains 90 mg of elemental calcium 1

Continuous Infusion Protocol

After the initial bolus, transition to a continuous infusion:

• Dilute 100 mL of 10% calcium gluconate (10 vials, containing 1000 mg total) in 1 liter of normal saline or 5% dextrose 2
• Infuse at 50-100 mL/hour, which delivers approximately 1-2 mg elemental calcium/kg/hour for a 70 kg patient 1
• The FDA-approved formulation contains 100 mg calcium gluconate per mL, providing 9.3 mg (0.4665 mEq) of elemental calcium per mL 3

Critical Monitoring Requirements

Measure ionized calcium levels:

• Every 4-6 hours during the first 48-72 hours post-initiation 1
• Every 1-4 hours during continuous infusion 3
• Then twice daily until stable 1

Continuous ECG monitoring is mandatory to detect arrhythmias, particularly in patients receiving cardiac glycosides 1, 2

Stop the infusion immediately if:

• Symptomatic bradycardia occurs 4
• Heart rate decreases by 10 beats per minute 4

Titration Strategy

• Gradually reduce the infusion rate when ionized calcium reaches and remains stable in the normal range (1.15-1.36 mmol/L) 1
• Adjust the infusion rate based on serial calcium measurements rather than using fixed dosing 1
• For moderate to severe hypocalcemia (iCa <1 mmol/L), a 4-gram infusion over 4 hours has shown 95% success in normalizing calcium levels 5

Administration Safety

Use a secure intravenous line, preferably central venous access 1, 4

• Peripheral administration carries significant risk of tissue necrosis and calcinosis cutis if extravasation occurs 4, 3
• Calcium gluconate is preferred over calcium chloride for peripheral administration due to less tissue irritation 4, 2
• If extravasation occurs, immediately discontinue the infusion at that site 3

Avoid rapid infusion to prevent cardiac arrhythmias, hypotension, bradycardia, and cardiac arrest 3

Transition to Oral Therapy

Once oral intake is possible and ionized calcium stabilizes:

• Administer calcium carbonate 1-2 grams three times daily 1
• Add calcitriol up to 2 mcg/day 1
• Adjust doses to maintain ionized calcium in the normal range 1

Special Populations and Considerations

In post-parathyroidectomy patients (the specific context where these guidelines were developed), this regimen prevents "hungry bone syndrome" 1

For renal impairment patients:

• Initiate at the lower end of the dosage range 3
• Monitor serum calcium every 4 hours 3

Drug incompatibilities:

• Do not mix with phosphate-containing or bicarbonate-containing fluids, as precipitation will occur 3
• Do not mix with vasoactive amines 4

Evidence Quality Note

The K/DOQI guidelines provide the most specific dosing recommendation (1-2 mg elemental calcium/kg/hour) for severe hypocalcemia, though this is opinion-based rather than evidence-based 1. Research in trauma patients supports that 4 grams of calcium gluconate effectively treats moderate to severe hypocalcemia (iCa <1 mmol/L) with 95% success 5, though individual response is highly variable 6, 7. The FDA labeling emphasizes individualized dosing within recommended ranges but defers to clinical judgment for specific rates 3.