Calcium Gluconate: Clinical Uses and Dosing
Primary Indications
Calcium gluconate is indicated for symptomatic acute hypocalcemia, life-threatening hyperkalemia with ECG changes, calcium channel blocker toxicity, and hypermagnesemia with cardiac manifestations. 1 Asymptomatic hypocalcemia does not require treatment, even in tumor lysis syndrome. 1, 2
Adult Dosing
Acute Symptomatic Hypocalcemia
- Administer 1–2 grams (10–20 mL of 10% solution) IV over 10 minutes with continuous ECG monitoring, followed by a continuous infusion. 1, 3
- For moderate-to-severe hypocalcemia (ionized calcium <1.0 mmol/L), give 2–4 grams IV infused at 1 gram/hour. 1, 4
- Continuous infusion protocol: Dilute 100 mL of 10% calcium gluconate (10 vials = 10 grams) in 1 liter of normal saline or 5% dextrose and infuse at 50–100 mL/hour (equivalent to 1–2 mg elemental calcium/kg/hour). 1, 2, 3
- Titrate the infusion rate to maintain ionized calcium in the normal range (1.15–1.36 mmol/L or 1.1–1.3 mmol/L). 1, 2
Hyperkalemia with ECG Changes
- Give 10 mL of 10% calcium gluconate IV over 2–5 minutes for membrane stabilization in severe hyperkalemia with cardiac manifestations. 1, 5
- This dose can be repeated if ECG abnormalities persist, though evidence shows calcium gluconate is most effective for main rhythm disorders (e.g., bradycardia, heart block) rather than non-rhythm ECG changes (e.g., peaked T-waves). 6
Calcium Channel Blocker Toxicity
- Administer 30–60 mL (3–6 grams) of 10% calcium gluconate IV every 10–20 minutes, or start a continuous infusion at 0.6–1.2 mL/kg/hour (0.06–0.12 g/kg/hour). 1
- Alternatively, give 0.6 mL/kg of 10% solution over 5–10 minutes, followed by an infusion of 0.3 mEq/kg per hour titrated to hemodynamic response. 1, 7
- Calcium gluconate is preferred over calcium chloride for peripheral IV administration due to less vein irritation. 1
Pediatric Dosing
Symptomatic Hypocalcemia
- Administer 50–100 mg/kg IV (of calcium gluconate salt, not elemental calcium) infused slowly over 30–60 minutes with continuous ECG monitoring. 1
- For mild hypocalcemia, the American Academy of Pediatrics recommends 60 mg/kg IV over 30–60 minutes. 1
Life-Threatening Situations (Seizures, Severe Arrhythmias)
- Give 100–200 mg/kg IV via slow infusion with continuous ECG monitoring for life-threatening hypocalcemic seizures or arrhythmias. 1
- In cardiac arrest, calcium can be given by slow push with careful heart rate monitoring. 1
Oral Dosing
Chronic Hypocalcemia Maintenance
- Calcium carbonate 1–2 grams three times daily (total elemental calcium should not exceed 2,000 mg/day). 2
- For chronic kidney disease patients with corrected calcium <8.5 mg/dL after phosphorus control, give 1 gram elemental calcium daily between meals or at bedtime. 2
- Consider adding calcitriol up to 2 μg/day to enhance intestinal calcium absorption, particularly in CKD patients with PTH >300 pg/mL. 2
Critical Administration Guidelines
Route and Vascular Access
- Central venous access is strongly preferred to prevent severe extravasation injury, calcinosis cutis, and tissue necrosis. 1, 7
- If only peripheral access is available, calcium gluconate is safer than calcium chloride, but the line must be secure and closely monitored. 1
Infusion Rate and Monitoring
- Avoid rapid infusion to prevent cardiac arrhythmias, symptomatic bradycardia, and hypotension. 1
- Stop the infusion immediately if heart rate decreases by ≥10 beats/minute or symptomatic bradycardia occurs. 1
- Maintain continuous ECG monitoring during all IV calcium administration. 1, 2
Monitoring Parameters
- Measure ionized calcium every 4–6 hours initially until stable, then twice daily. 1, 2
- Target ionized calcium >0.9 mmol/L minimum (optimal range 1.1–1.3 mmol/L). 2
- Monitor serum magnesium, as hypomagnesemia (present in 28% of hypocalcemic ICU patients) prevents calcium correction and must be repleted first. 2
Contraindications and Critical Precautions
Absolute Contraindications
- Never mix calcium gluconate with sodium bicarbonate in the same IV line—precipitation will occur. 1, 2
- Do not mix with phosphate-containing fluids or vasoactive amines (epinephrine, dopamine). 1
Relative Contraindications and Cautions
- Exercise extreme caution when serum phosphate is elevated (e.g., tumor lysis syndrome, renal failure)—calcium administration increases the risk of calcium-phosphate precipitation in tissues, causing obstructive uropathy. 1
- Consider renal consultation before aggressive calcium replacement in hyperphosphatemic patients. 1
- Avoid calcium administration in digoxin-toxic patients whenever possible; if absolutely necessary, give slowly in small amounts with close ECG monitoring, as calcium may precipitate life-threatening arrhythmias. 1
Special Clinical Situations
Massive Transfusion
- Titrate calcium chloride (preferred over gluconate) to maintain ionized calcium >0.9 mmol/L during massive transfusion, as citrate anticoagulant chelates calcium. 2
- Hypocalcemia is exacerbated by hypothermia, hypoperfusion, and hepatic insufficiency, which impair citrate metabolism. 2
- No fixed calcium-to-blood-product ratio is recommended; titrate to measured ionized calcium levels. 2
Post-Parathyroidectomy
- Measure ionized calcium every 4–6 hours for the first 48–72 hours, then twice daily until stable. 1
- If ionized calcium falls below 0.9 mmol/L, initiate calcium gluconate infusion at 1–2 mg elemental calcium/kg/hour. 1
- Gradually reduce the infusion when calcium normalizes and transition to oral calcium carbonate and calcitriol. 1
Tumor Lysis Syndrome
- Treat only symptomatic patients—asymptomatic hypocalcemia does not require calcium replacement. 1, 2
- If symptoms occur (tetany, seizures), give a single cautious dose of 50–100 mg/kg IV and repeat only if symptoms persist. 1
Adverse Effects
Cardiac
- Bradycardia and arrhythmias (especially with rapid infusion or in digoxin-treated patients). 1
- Hypotension if administered too rapidly. 1
Local
- Severe tissue necrosis and calcinosis cutis from extravasation, particularly with peripheral IV administration. 1, 7
- Vein irritation (less than calcium chloride but still significant). 1
Metabolic
- Iatrogenic hypercalcemia from overcorrection, which can cause renal calculi and renal failure. 2
- Avoid ionized calcium levels greater than twice the upper limit of normal. 7
Calcium Gluconate vs. Calcium Chloride
Calcium chloride provides approximately three times more elemental calcium per unit volume (270 mg vs. 90 mg per 10 mL of 10% solution) and raises ionized calcium more rapidly. 2, 8, 3 However, calcium gluconate is preferred for peripheral IV administration due to significantly less tissue irritation. 1 In cardiac arrest, liver dysfunction, hypothermia, or shock states where rapid ionization is critical, calcium chloride is preferred and should be given via central line only. 2, 8
Common Pitfalls
- Treating asymptomatic hypocalcemia is unnecessary and potentially harmful. 1, 2
- Failing to check and correct magnesium before or during calcium replacement—hypocalcemia cannot be fully corrected without adequate magnesium. 2
- Using peripheral IV for calcium chloride—this formulation is highly caustic and should only be given centrally. 1
- Ignoring elevated phosphate levels—aggressive calcium replacement in hyperphosphatemia causes tissue calcification. 1
- Relying on standard coagulation tests in hypocalcemic patients—PT/PTT may appear normal because laboratory samples are recalcified before analysis, masking true coagulopathy. 2
- Mixing calcium with bicarbonate or phosphate solutions—this causes immediate precipitation. 1, 2