What is the recommended intravenous calcium dose for an infant presenting with a hypocalcemic seizure?

Intravenous Calcium Dose for Hypocalcemic Seizure in Infants

For an infant presenting with hypocalcemic seizure, administer 100-200 mg/kg of 10% calcium gluconate intravenously as a slow infusion over 5-10 minutes with continuous cardiac monitoring. 1

Initial Emergency Management

Immediate Calcium Bolus

• Give 100-200 mg/kg of 10% calcium gluconate IV for life-threatening hypocalcemic seizures with arrhythmias 1
• For less severe symptomatic hypocalcemia, use 50-100 mg/kg of calcium gluconate IV infused slowly over 30-60 minutes 2
• Alternatively, 20 mg/kg (0.2 mL/kg) of 10% calcium chloride IV can be used, which provides more rapid increase in ionized calcium than calcium gluconate and is preferred for critically ill infants 1, 3

Critical Administration Guidelines

• Infuse slowly over 5-10 minutes for the initial bolus to prevent cardiac complications 3, 4
• Maximum rate: do not exceed 1 mL/min when administering calcium chloride 4
• Continuous ECG monitoring is mandatory during administration to detect bradycardia or arrhythmias 1, 2
• Stop the infusion immediately if heart rate decreases by 10 beats per minute or symptomatic bradycardia occurs 1, 2

Route and Access Considerations

Preferred Vascular Access

• Central venous access is strongly preferred for calcium administration, as extravasation through peripheral IV lines may cause severe skin and soft tissue injury 1, 2
• If only peripheral access is available, calcium gluconate is preferred over calcium chloride because it is less caustic to veins 2, 3
• Calcium chloride should only be given via central line due to its irritant properties 1, 5

Dose Equivalence

• 10 mL of 10% calcium gluconate contains 2.2 mmol (90 mg) of elemental calcium 2, 5
• 10 mL of 10% calcium chloride contains 27 mg/mL or 270 mg of elemental calcium 4
• Calcium chloride provides approximately three times more elemental calcium per volume than calcium gluconate 1, 5

Maintenance Therapy After Initial Bolus

Continuous Infusion Protocol

• Following the initial bolus, start a continuous calcium gluconate infusion by diluting 100 mL of 10% calcium gluconate (10 vials) in 1 L of normal saline or 5% dextrose 5
• Infuse at 50-100 mL/hour and titrate to maintain normocalcemia 5
• For pediatric dosing, 1-2 mg elemental calcium per kg per hour is recommended 2

Monitoring Requirements

• Measure ionized calcium every 4-6 hours for the first 48-72 hours, then twice daily until stable 2, 6
• Monitor serum phosphorus levels before aggressive calcium replacement, as elevated phosphate increases risk of calcium-phosphate precipitation causing obstructive uropathy 2
• Repeated doses may be required because of rapid renal excretion of calcium 4

Special Considerations for Neonatal Hypocalcemia

Etiology-Specific Management

• Early neonatal hypocalcemia (first 72 hours) is often due to interruption of placental calcium transfer and relative immaturity of hormonal control 3
• If maternal hyperparathyroidism or excessive maternal calcium ingestion is suspected, the infant may have transient neonatal hypoparathyroidism requiring several days of IV calcium therapy 6, 7
• Treatment with IV calcium gluconate over several days may be needed until serum calcium normalizes and seizures cease 7

Alternative Route in Special Circumstances

• If stable IV access cannot be maintained, continuous nasogastric calcium carbonate at 125 mg elemental calcium/kg/day can be considered as an alternative, though this is not standard practice 6
• This enteral approach avoids complications of peripheral or central IV calcium but should only be used after initial IV bolus has controlled seizures 6

Critical Safety Precautions

Drug Interactions and Contraindications

• Never mix calcium with sodium bicarbonate in the same IV line, as precipitation will occur 1, 2
• Do not mix calcium with vasoactive amines (epinephrine, dopamine, etc.) 1, 2
• Avoid calcium administration in patients receiving digoxin whenever possible; if absolutely necessary, give slowly in small amounts with close ECG monitoring 2

Common Pitfalls to Avoid

• Do not treat asymptomatic hypocalcemia, even in tumor lysis syndrome, as it is unnecessary and potentially harmful 2
• Avoid rapid infusion, which can cause hypotension, bradycardia, and cardiac arrhythmias 2
• Do not administer calcium if serum phosphate is markedly elevated without first consulting nephrology, due to risk of tissue calcification 2
• Ensure adequate urine output before initiating calcium replacement to confirm renal function 3

Transition to Oral Therapy

Once seizures are controlled and calcium levels stabilize, transition to oral calcium carbonate, calcitriol, and cholecalciferol for maintenance therapy 6. Most infants with transient neonatal hypoparathyroidism can have all medications discontinued by 8 weeks of age 6.