Calcium Drip Computation for Hypocalcemia
Immediate Recommendation
For acute symptomatic hypocalcemia requiring continuous infusion, administer calcium gluconate 4 grams IV infused at 1 gram/hour over 4 hours for moderate to severe hypocalcemia (ionized calcium <1.0 mmol/L), or 1-2 grams for mild hypocalcemia (ionized calcium 1.0-1.12 mmol/L). 1, 2, 3
Agent Selection: Calcium Chloride vs Calcium Gluconate
Calcium chloride is strongly preferred 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. 4, 5
However, calcium gluconate is preferred for peripheral IV administration due to significantly less tissue irritation and lower risk of severe skin necrosis from extravasation. 1, 5, 6
Elemental Calcium Content
- Calcium chloride 10%: 270 mg elemental calcium per 10 mL (27 mg/mL) 5, 7
- Calcium gluconate 10%: 90 mg elemental calcium per 10 mL (9.3 mg/mL) 1, 8
Dosing Protocols by Severity
Mild Hypocalcemia (ionized Ca 1.0-1.12 mmol/L)
- Adults: 1-2 grams calcium gluconate IV infused at 1 gram/hour 1, 2
- Pediatrics: 60 mg/kg calcium gluconate infused over 30-60 minutes 1
- Success rate: 79% achieve normalization with this regimen 2
Moderate to Severe Hypocalcemia (ionized Ca <1.0 mmol/L)
- Adults: 2-4 grams calcium gluconate IV infused at 1 gram/hour 1, 2, 3
- Optimal regimen: 4 grams achieves ionized calcium >1.0 mmol/L in 95% of critically ill trauma patients 3
- Pediatrics: 50-100 mg/kg calcium gluconate IV infused slowly over 30-60 minutes 4, 1
Life-Threatening Hypocalcemia with Arrhythmias
- Pediatrics: 100-200 mg/kg calcium gluconate via slow infusion with continuous ECG monitoring 4, 1
- Adults: 5-10 mL (500-1000 mg) calcium chloride 10% IV over 2-5 minutes with cardiac monitoring 5
Administration Protocol
Infusion Rate and Monitoring
- Maximum infusion rate: 1 gram/hour for calcium gluconate to prevent cardiac arrhythmias 7, 2, 3
- Calcium chloride bolus: Not to exceed 1 mL/min (100 mg/min) 7
- Continuous ECG monitoring is mandatory during all calcium infusions 1, 5, 7
- Stop infusion immediately if symptomatic bradycardia occurs or heart rate decreases by 10 beats per minute 1
Laboratory Monitoring
- During intermittent infusions: Measure ionized calcium every 4-6 hours 8
- During continuous infusions: Measure ionized calcium every 1-4 hours 8
- Target ionized calcium: Maintain >0.9 mmol/L minimum, optimal range 1.15-1.36 mmol/L 5
Dilution and Preparation
- Dilute calcium gluconate in 50-100 mL of 0.9% NaCl or 5% dextrose 8
- Warm solution to body temperature if time permits 7
- Use central venous access whenever possible to minimize extravasation risk 1, 5
Critical Pitfalls and Contraindications
Absolute Incompatibilities
- Never mix calcium with sodium bicarbonate - causes immediate precipitation 4, 1, 5, 8
- Never mix with phosphate-containing fluids - causes precipitation 8
- Never mix with vasoactive amines 1, 5
Special Precautions
- In hyperphosphatemia: Exercise extreme caution as calcium administration increases risk of calcium-phosphate precipitation in tissues causing obstructive uropathy; consider renal consultation before aggressive replacement 4, 1
- With cardiac glycosides: Synergistic arrhythmias may occur; if concomitant therapy necessary, give calcium slowly in small amounts with close ECG monitoring 8
- Correct magnesium deficiency first - hypocalcemia cannot be fully corrected without adequate magnesium 5
Extravasation Management
- Immediately discontinue infusion if extravasation occurs or calcinosis cutis develops 8
- Tissue necrosis, ulceration, and secondary infection are the most serious complications 8
Special Clinical Contexts
Massive Transfusion/Trauma
- Transfusion-induced hypocalcemia with ionized calcium <0.9 mmol/L should be corrected promptly 4
- Ionized calcium <0.8 mmol/L is associated with cardiac dysrhythmias 4
- Calcium chloride is preferred in this setting due to impaired hepatic citrate metabolism 4, 5
Tumor Lysis Syndrome
- For asymptomatic hypocalcemia: No intervention recommended 4
- For symptomatic patients: Calcium gluconate 50-100 mg/kg IV administered slowly with ECG monitoring 4
Calcium Channel Blocker Toxicity
- Initial bolus: 30-60 mL (3-6 grams) calcium gluconate 10% IV every 10-20 minutes 1
- Continuous infusion: 0.6-1.2 mL/kg/hour (0.06-0.12 g/kg/hour) calcium gluconate 1
Pediatric-Specific Dosing
Calcium Chloride
- 20 mg/kg (0.2 mL/kg of 10% solution) IV/IO for acute symptomatic hypocalcemia 5
- Administer by slow push for cardiac arrest or infuse over 30-60 minutes for other indications 5