Intravenous Calcium Gluconate Dosing for Hypocalcemia
For symptomatic hypocalcemia in adults, administer 1–2 grams of calcium gluconate IV infused over 30–60 minutes with continuous ECG monitoring; for children, give 50–100 mg/kg IV over the same duration. 1
Adult Dosing by Severity
Mild Hypocalcemia (ionized Ca 1.0–1.12 mmol/L)
- Administer 1–2 grams of calcium gluconate IV infused at 1 gram/hour. 2
- This dose normalizes ionized calcium in approximately 79% of patients with mild hypocalcemia. 3
Moderate to Severe Hypocalcemia (ionized Ca <1.0 mmol/L)
- Give 4 grams of calcium gluconate IV infused at 1 gram/hour over 4 hours. 2, 4
- This regimen successfully raises ionized calcium above 1.0 mmol/L in 95% of patients and above 1.12 mmol/L in 70% of patients. 4
- For life-threatening symptoms or cardiac arrhythmias, an initial bolus of 1–2 grams (10–20 mL of 10% solution) may be given over 10 minutes with ECG monitoring, followed by continuous infusion. 1, 5
Post-Parathyroidectomy Protocol
- When ionized calcium falls below 0.9 mmol/L (<3.6 mg/dL), initiate a continuous calcium gluconate infusion at 1–2 mg elemental calcium per kg per hour. 6
- Measure ionized calcium every 4–6 hours for the first 48–72 hours, then twice daily until stable. 6
- Adjust the infusion rate to maintain ionized calcium in the normal range (1.15–1.36 mmol/L or 4.6–5.4 mg/dL). 6
- Remember that each 10 mL ampule of 10% calcium gluconate contains 90 mg of elemental calcium. 6
Pediatric Dosing
Standard Symptomatic Hypocalcemia
- Administer 50–100 mg/kg of calcium gluconate IV infused slowly over 30–60 minutes with continuous ECG monitoring. 1, 2
- For mild hypocalcemia, the American Academy of Pediatrics recommends 60 mg/kg infused over 30–60 minutes. 1
Life-Threatening Situations (Seizures, Severe Arrhythmias)
- Give 100–200 mg/kg of calcium gluconate via slow IV infusion with continuous ECG monitoring. 1
- Stop the infusion immediately if heart rate decreases by 10 beats per minute or symptomatic bradycardia occurs. 1
Administration Guidelines
Route and Monitoring
- Administer through a central venous catheter whenever possible to minimize the risk of severe extravasation injury and tissue necrosis. 1
- Calcium gluconate is preferred over calcium chloride for peripheral administration because it causes significantly less vein irritation. 1, 2
- Continuous ECG monitoring is mandatory during all calcium infusions to detect bradycardia or arrhythmias. 1
Infusion Rate
- For non-emergent situations, infuse at 1 gram/hour to minimize cardiac complications. 2, 7, 4
- For cardiac arrest or life-threatening hyperkalemia, 10–30 mL of 10% calcium gluconate can be given over 2–10 minutes. 1
- Never administer rapid infusions in non-arrest situations, as this increases the risk of cardiac arrhythmias and symptomatic bradycardia. 1
Critical Drug Incompatibilities
Never mix calcium gluconate with the following:
- Sodium bicarbonate – causes immediate precipitation. 1, 2
- Phosphate-containing fluids – causes precipitation. 1, 2
- Vasoactive amines (epinephrine, dopamine) – avoid mixing in the same line. 1
Special Clinical Contexts
Calcium Channel Blocker Toxicity
- Administer 30–60 mL (3–6 grams) of 10% calcium gluconate IV every 10–20 minutes, or as a continuous infusion at 0.6–1.2 mL/kg/hour (0.06–0.12 g/kg/hour). 1
- Titrate based on hemodynamic response rather than fixed schedules. 1
Tumor Lysis Syndrome
- Exercise extreme caution when phosphate levels are elevated – additional calcium may precipitate calcium-phosphate crystals in tissues, causing obstructive uropathy. 1
- Consider renal consultation before aggressive calcium replacement in this setting. 1
- Treat only symptomatic patients; asymptomatic hypocalcemia does not require calcium replacement. 1
Massive Transfusion
- Maintain ionized calcium >0.9 mmol/L minimum, with an optimal target of 1.1–1.3 mmol/L. 8
- Consider using calcium chloride instead of calcium gluconate in this setting, as it provides three times more elemental calcium per volume (270 mg vs 90 mg per 10 mL) and is more effective when citrate metabolism is impaired by hypothermia, hypoperfusion, or hepatic dysfunction. 2, 8
Essential Cofactor Correction
Always check and correct magnesium deficiency before or alongside calcium therapy – hypocalcemia cannot be fully corrected without adequate magnesium, and hypomagnesemia is present in 28% of hypocalcemic ICU patients. 2, 8
Monitoring During Treatment
- Measure ionized calcium every 4–6 hours during initial treatment until stable, then twice daily. 6, 8
- During continuous infusion, measure every 1–4 hours. 9
- Reassess ionized calcium approximately 10 hours after completion of bolus infusion to ensure equilibration and assess efficacy. 7
Common Pitfalls to Avoid
- Do not treat asymptomatic hypocalcemia – even in tumor lysis syndrome, asymptomatic patients do not require calcium replacement. 1
- Avoid calcium administration in patients on digoxin whenever possible; if absolutely necessary, give slowly in small amounts with close ECG monitoring to prevent precipitating digoxin toxicity. 1
- Do not ignore mild hypocalcemia in critically ill patients – even mild reductions impair the coagulation cascade and platelet function. 8
- Beware of overcorrection – iatrogenic hypercalcemia can cause renal calculi and renal failure. 8
- Standard coagulation tests (PT/PTT) may appear falsely normal despite significant hypocalcemia-induced coagulopathy because laboratory samples are recalcified before analysis. 8