What is the recommended dosage and administration of calcium gluconate for treating hypocalcemia?

Calcium Gluconate Dosing and Administration for Hypocalcemia

For severe symptomatic hypocalcemia, initiate a continuous intravenous infusion of calcium gluconate 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 or 4.6-5.4 mg/dL). 1

Preparation and Concentration

• Each 10 mL ampule of 10% calcium gluconate contains 90 mg of elemental calcium 1, 2
• The standard concentration is 100 mg calcium gluconate per mL, which provides 9.3 mg (0.4665 mEq) of elemental calcium 3
• For a 70 kg patient, infuse at 50-100 mL/hour to deliver approximately 1-2 mg elemental calcium/kg/hour 2

Route and Administration Safety

• Administer intravenously via a secure line, preferably central venous access 2, 3
• Dilute with 5% dextrose or normal saline before infusion 3
• Never mix calcium gluconate with phosphate-containing or bicarbonate-containing fluids—precipitation will occur 1, 3
• Do not administer through the same line as sodium bicarbonate 1
• Infuse at a rate of 1 g/hour in small-volume admixtures 4, 5

Dosing by Severity and Age

Symptomatic Hypocalcemia in Pediatrics

• Administer calcium gluconate 50-100 mg/kg IV slowly with continuous ECG monitoring 1
• For life-threatening arrhythmias from hyperkalemia, give 100-200 mg/kg/dose via slow infusion with ECG monitoring for bradycardia 1

Symptomatic Hypocalcemia in Adults

• For moderate to severe hypocalcemia (ionized calcium <1 mmol/L), administer 4 g of calcium gluconate infused over 4 hours 5
• This regimen successfully achieves ionized calcium >1 mmol/L in 95% of critically ill patients 5
• For mild hypocalcemia (ionized calcium 1-1.12 mmol/L), 1-2 g of IV calcium gluconate is effective in normalizing calcium in 79% of patients 4

Post-Parathyroidectomy

• If ionized calcium falls below 0.9 mmol/L (corresponding to corrected total calcium of 7.2 mg/dL), initiate calcium gluconate infusion at 1-2 mg elemental calcium/kg/hour 1

Monitoring Requirements

During Continuous Infusion

• Measure ionized calcium every 1-4 hours during continuous infusion 3
• For the first 48-72 hours, measure ionized calcium every 4-6 hours, then twice daily until stable 1, 2
• Maintain continuous ECG monitoring, particularly when administering to patients on cardiac glycosides 3
• Stop the infusion immediately if symptomatic bradycardia occurs or heart rate decreases by 10 beats per minute 2

During Intermittent Infusions

• Measure serum calcium every 4-6 hours 3

Titration and Transition

• Gradually reduce the infusion rate when ionized calcium reaches and remains stable in the normal range 1, 2
• Adjust the infusion rate based on serial calcium measurements rather than using fixed dosing 2
• Once oral intake is possible and ionized calcium stabilizes, transition to calcium carbonate 1-2 grams three times daily plus calcitriol up to 2 mcg/day 1, 2
• Continue adjusting doses to maintain ionized calcium in the normal range 1, 2

Critical Safety Warnings

Cardiac Considerations

• If concomitant cardiac glycoside therapy is necessary, administer calcium gluconate slowly in small amounts with close ECG monitoring—synergistic arrhythmias may occur 3
• Rapid administration can cause hypotension, bradycardia, cardiac arrhythmias, syncope, and cardiac arrest 3

Extravasation and Tissue Damage

• Calcinosis cutis can occur with or without extravasation, leading to tissue necrosis, ulceration, and secondary infection 3
• If extravasation occurs or clinical manifestations of calcinosis cutis are noted, immediately discontinue administration at that site 3

Special Populations

• Calcium gluconate is contraindicated in neonates (28 days or younger) receiving ceftriaxone due to risk of fatal intravascular precipitates 3
• Concurrent use of intravenous ceftriaxone in any patient may cause life-threatening precipitates and end-organ damage 3

Clinical Context and Pitfalls

• Asymptomatic hypocalcemia does not require immediate intervention 1
• In tumor lysis syndrome, exercise caution with calcium replacement when phosphate levels are elevated—increased calcium may increase the risk of calcium phosphate precipitation in tissues and obstructive uropathy 1
• Consider renal consultation if phosphate levels are high before administering calcium 1
• The individual response to calcium therapy is highly variable, even when normalized to body weight 4
• Hypocalcemia in critically ill patients usually normalizes within four days, and failure to normalize in severely hypocalcemic patients may be associated with increased mortality 6
• Calcium replacement does not appear to improve normalization rates or mortality compared to no supplementation in observational studies 6