IV Calcium Treatment for Symptomatic Hypocalcemia
For acute symptomatic hypocalcemia in adults, administer calcium gluconate 1-2 grams IV for mild hypocalcemia (ionized Ca 1.0-1.12 mmol/L) or 2-4 grams for moderate to severe hypocalcemia (ionized Ca <1.0 mmol/L), infused at 1 gram/hour over 30-60 minutes with continuous ECG monitoring. 1
Dosing Based on Severity
Mild Hypocalcemia (ionized Ca 1.0-1.12 mmol/L)
- Adults: 1-2 grams calcium gluconate IV infused at 1 gram/hour 1
- Pediatrics: 60 mg/kg calcium gluconate infused over 30-60 minutes 2
Moderate to Severe Hypocalcemia (ionized Ca <1.0 mmol/L)
- Adults: 2-4 grams calcium gluconate IV infused at 1 gram/hour 1
- Pediatrics: 50-100 mg/kg calcium gluconate IV infused slowly over 30-60 minutes 2, 1
Life-Threatening Arrhythmias
- 100-200 mg/kg/dose calcium gluconate via slow infusion with ECG monitoring for bradycardia 2
- For cardiac arrest or severe hyperkalemia: 10-30 mL of 10% calcium gluconate over 2-10 minutes with continuous ECG monitoring 2
Agent Selection: Calcium Gluconate vs Calcium Chloride
Calcium gluconate is strongly preferred for peripheral IV administration due to significantly less tissue irritation and lower risk of severe skin necrosis from extravasation 1. However, there are critical exceptions:
- Use calcium chloride in trauma, massive transfusion, and critically ill patients with liver dysfunction because it delivers 3 times more elemental calcium (270 mg per 10 mL vs 90 mg per 10 mL) and produces more rapid increases in ionized calcium without requiring hepatic metabolism 1
- Calcium chloride should only be given via central line due to vein irritation 2
Administration Protocol
Route and Monitoring
- Administer through a secure IV line, preferably central venous catheter 2
- Continuous ECG monitoring is mandatory during administration 2
- Stop infusion immediately if heart rate decreases by 10 beats per minute or symptomatic bradycardia occurs 2
Infusion Rate
- Standard rate: 1 gram/hour for adults 1
- Dilute in 50-100 mL of 5% dextrose or normal saline 3
- Avoid rapid infusion to prevent hypotension, bradycardia, and cardiac arrhythmias 2
Laboratory Monitoring
- Measure serum calcium every 4-6 hours during intermittent infusions 3
- Measure every 1-4 hours during continuous infusion 3
Critical Pitfalls and Contraindications
Absolute Incompatibilities
- Never mix calcium with sodium bicarbonate - causes immediate precipitation 1
- Never mix calcium with phosphate-containing fluids - causes precipitation 1, 3
- Do not mix with vasoactive amines 2, 1
Magnesium Deficiency
- Correct magnesium deficiency first - hypocalcemia cannot be fully corrected without adequate magnesium 1
Elevated Phosphate
- Exercise caution when phosphate levels are elevated, as increased calcium may precipitate calcium phosphate in tissues causing obstructive uropathy 2
- Consider renal consultation before aggressive calcium replacement in hyperphosphatemia 2
Cardiac Glycosides
- If concomitant cardiac glycoside therapy is necessary, calcium gluconate should be given slowly in small amounts with close ECG monitoring due to synergistic arrhythmia risk 3
Special Clinical Contexts
Post-Parathyroidectomy
- Measure ionized calcium every 4-6 hours for first 48-72 hours, then twice daily until stable 2
- For ionized calcium below 0.9 mmol/L, initiate calcium gluconate infusion at 1-2 mg elemental calcium per kg per hour 2
- Adjust infusion rate to maintain ionized calcium in normal range (1.15-1.36 mmol/L) 2
Tumor Lysis Syndrome
- Asymptomatic hypocalcemia does not require treatment, even in tumor lysis syndrome 2
- For symptomatic patients: calcium gluconate 50-100 mg/kg IV administered slowly with ECG monitoring 1
Calcium Channel Blocker Toxicity
- Administer 30-60 mL (3-6 grams) of 10% calcium gluconate IV every 10-20 minutes, or as continuous infusion at 0.6-1.2 mL/kg/hour 2
Extravasation Management
If extravasation occurs or clinical manifestations of calcinosis cutis are noted, immediately discontinue IV administration at that site 3. Tissue necrosis, ulceration, and secondary infection are the most serious complications 3. Early debridement and split-thickness skin graft may be necessary for established skin necrosis 4.