What is the recommended dose and administration of a calcium gluconate drip for treating hypocalcemia?

Calcium Gluconate Drip for Hypocalcemia

For acute symptomatic hypocalcemia, administer calcium gluconate 1-2 mg elemental calcium per kg body weight per hour as a continuous infusion, adjusting to maintain ionized calcium in the normal range (1.15-1.36 mmol/L or 4.6-5.4 mg/dL). 1

Dosing Fundamentals

One 10 mL ampule of 10% calcium gluconate contains 90 mg of elemental calcium (2.2 mmol). 1, 2 This is critical for calculating infusion rates accurately.

Initial Bolus Dosing

For severe symptomatic hypocalcemia (ionized calcium <0.9 mmol/L or corrected total calcium <7.2 mg/dL):

• Administer 10-20 mL of 10% calcium gluconate 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 symptoms resolve 2
• In pediatric patients, the FDA-approved dosing should be individualized based on severity, with the bolus administered slowly with ECG monitoring 3

Continuous Infusion Protocol

Following the initial bolus, initiate a continuous calcium gluconate infusion: 1

• Dilute 100 mL of 10% calcium gluconate (10 ampules = 900 mg elemental calcium) in 1 liter of normal saline or 5% dextrose 2
• Infuse at 50-100 mL/hour, which delivers approximately 1-2 mg elemental calcium per kg body weight per hour for a 70 kg adult 1
• Titrate the infusion rate to maintain ionized calcium in the normal range (1.15-1.36 mmol/L) 1

Monitoring Requirements

Measure ionized calcium levels every 4-6 hours during intermittent infusions and every 1-4 hours during continuous infusion. 1, 3

• In post-parathyroidectomy patients, measure ionized calcium every 4-6 hours for the first 48-72 hours, then twice daily until stable 1
• Continuous ECG monitoring is essential during administration to detect arrhythmias, particularly bradycardia and QT interval changes 3, 2

Critical Administration Considerations

Infusion Rate and Safety

Rapid administration causes life-threatening complications including hypotension, bradycardia, cardiac arrhythmias, syncope, and cardiac arrest. 3 Always dilute and infuse slowly.

Administer through a secure, patent intravenous line—preferably central venous access—as extravasation causes severe tissue necrosis, ulceration, calcinosis cutis, and secondary infection. 3 If extravasation occurs, immediately discontinue the infusion at that site.

Drug Incompatibilities

Calcium gluconate is NOT physically compatible with fluids containing phosphate or bicarbonate—precipitation will occur if mixed. 3 Never administer through the same line as sodium bicarbonate. 1, 4

Exercise extreme caution when phosphate levels are elevated due to risk of calcium-phosphate precipitation in tissues. 4

Special Populations

In patients receiving cardiac glycosides (digoxin), calcium administration potentiates toxicity and causes synergistic arrhythmias. 3 If concomitant therapy is unavoidable, give calcium gluconate very slowly in small amounts with close ECG monitoring.

Never administer calcium gluconate to neonates (≤28 days) receiving ceftriaxone—fatal intravascular precipitates have occurred. 3

Context-Specific Dosing

Post-Parathyroidectomy "Hungry Bone Syndrome"

This represents the most aggressive hypocalcemia requiring the highest calcium replacement:

• Start infusion at 1-2 mg elemental calcium/kg/hour immediately if ionized calcium falls below 0.9 mmol/L 1
• Gradually reduce infusion when ionized calcium reaches and remains stable in the normal range 1
• Transition to oral calcium carbonate 1-2 g three times daily plus calcitriol up to 2 mcg/day when oral intake is tolerated 1

Moderate to Severe Hypocalcemia in Trauma Patients

For ionized calcium <1 mmol/L in critically ill trauma patients, a 4-gram calcium gluconate infusion over 4 hours (1 g/hour) successfully corrects hypocalcemia in 95% of cases. 5 This is more effective than the 2-4 gram range, which only achieved correction in 38% of patients. 6

Mild Hypocalcemia (ionized calcium 1.0-1.12 mmol/L)

Administer 1-2 grams of calcium gluconate intravenously, which normalizes ionized calcium in 79% of patients with mild hypocalcemia. 6

Common Pitfalls

The individual response to calcium therapy is highly variable—some patients require substantially more or less than weight-based calculations predict. 6 This underscores the critical importance of frequent ionized calcium monitoring rather than relying solely on calculated doses.

Overcorrection causes iatrogenic hypercalcemia, renal calculi, and renal failure. 4, 7 Target the low-normal calcium range (8.4-9.5 mg/dL or 2.10-2.37 mmol/L) rather than mid-normal values.

In trauma patients, hypocalcemia often results from citrate in blood products binding calcium, and citrate metabolism is impaired by hypoperfusion, hypothermia, and hepatic insufficiency. 4 Monitor ionized calcium closely during massive transfusion protocols.

Always correct concurrent hypomagnesemia before or during calcium replacement—hypomagnesemia impairs PTH secretion and causes end-organ PTH resistance, making calcium supplementation alone ineffective. 4, 7

Duration of Therapy

Continue the calcium gluconate infusion until treatment of the underlying cause has taken effect. 2 The safety of calcium gluconate for long-term use has not been established. 3

For chronic hypocalcemia management, transition to oral calcium and vitamin D supplementation with regular monitoring of pH-corrected ionized calcium, magnesium, PTH, and creatinine. 4, 7