Calcium Gluconate: Clinical Guide
Primary Indications
Calcium gluconate is indicated for symptomatic acute hypocalcemia and severe hyperkalemia with ECG changes, but should NOT be given for asymptomatic hypocalcemia. 1, 2
Symptomatic Hypocalcemia
- Administer 50-100 mg/kg IV slowly over 30-60 minutes with continuous ECG monitoring for symptomatic acute hypocalcemia in both pediatric and adult patients 1, 2, 3
- For adults with moderate to severe hypocalcemia (ionized calcium <1 mmol/L), give 2-4 grams IV calcium gluconate 3
- Asymptomatic hypocalcemia requires NO treatment, even in tumor lysis syndrome 1, 3
Severe Hyperkalemia with ECG Changes
- For severe hyperkalemia (≥6.5 mEq/L) or any potassium level with ECG changes (peaked T waves, widened QRS, prolonged PR interval), give 10% calcium gluconate 15-30 mL (1.5-3 grams) IV over 2-5 minutes 2, 4, 5
- Calcium acts as cardioprotection by stabilizing myocardial membranes but does NOT lower potassium levels 4
- Effects begin within minutes but last only 30-60 minutes, requiring combination with potassium-lowering therapies 4
- Recent evidence shows calcium gluconate is effective primarily for main rhythm disorders (e.g., bradycardia, heart block) but has limited efficacy for non-rhythm ECG changes like peaked T waves alone 6
Life-Threatening Arrhythmias
- For pediatric patients with life-threatening arrhythmias from hyperkalemia, give 100-200 mg/kg/dose via slow infusion with ECG monitoring 1, 2
Dosing Regimens by Clinical Scenario
Mild Hypocalcemia
- 60 mg/kg IV infused over 30-60 minutes 3
Moderate to Severe Hypocalcemia (Adults)
- 2-4 grams IV calcium gluconate infused over 30-60 minutes 3
- For critically ill trauma patients, 1-2 grams was effective in 79% with mild hypocalcemia but only 38% with moderate-severe hypocalcemia, indicating higher doses or continuous infusion may be needed 7
Post-Parathyroidectomy Hypocalcemia
- Initiate continuous infusion at 1-2 mg elemental calcium per kg per hour for ionized calcium <0.9 mmol/L 3
- Target ionized calcium 1.15-1.36 mmol/L with measurements every 4-6 hours for first 48-72 hours 3
- Note: 10 mL of 10% calcium gluconate contains only 90 mg elemental calcium 3
Calcium Channel Blocker Toxicity
- Give 30-60 mL (3-6 grams) of 10% calcium gluconate IV every 10-20 minutes, or as continuous infusion at 0.6-1.2 mL/kg/hour 3
Critical Administration Requirements
ECG Monitoring (MANDATORY)
- Continuous ECG monitoring is required during ALL calcium gluconate administration 2, 3
- Stop infusion immediately if heart rate decreases by 10 beats per minute or symptomatic bradycardia occurs 2, 3
- Even "slow push" administration over 5-10 minutes carries arrhythmia risk 3
Vascular Access
- Central venous catheter is strongly preferred 2, 3
- Peripheral IV extravasation can cause severe skin and soft tissue injury 2, 3
- If only peripheral access available, ensure line is secure and monitor closely 3
- Calcium gluconate is preferred over calcium chloride for peripheral administration due to less tissue irritation 3, 4
Rate of Administration
- For non-emergent hypocalcemia: infuse over 30-60 minutes 2, 3
- For cardiac arrest or life-threatening hyperkalemia: 10-30 mL over 2-10 minutes with continuous ECG monitoring 3, 4
- Avoid rapid infusion to prevent cardiac arrhythmias, hypotension, and symptomatic bradycardia 3
Absolute Contraindications and Critical Precautions
Do NOT Mix With:
- Never administer sodium bicarbonate and calcium through the same IV line due to precipitation risk 1, 2, 3
- Do not mix with phosphate-containing fluids (will precipitate) 3
- Do not mix with vasoactive amines 3
Hyperphosphatemia Warning
- Exercise extreme caution when phosphate levels are elevated 1, 3
- Increased calcium administration increases risk of calcium phosphate precipitation in tissues, causing obstructive uropathy 1, 3
- Consider renal consultation before aggressive calcium replacement in hyperphosphatemia 3
Digoxin Interaction
- Avoid calcium administration if possible in patients on digoxin 3
- If absolutely necessary, give slowly in small amounts with close ECG monitoring 3
- Calcium can precipitate digoxin toxicity and life-threatening arrhythmias 3
Hyperkalemia Treatment Algorithm
When treating hyperkalemia, calcium is only ONE component of a three-step approach:
Step 1: Cardiac Membrane Stabilization (Immediate - 0-5 minutes)
- Calcium gluconate 10%: 15-30 mL IV over 2-5 minutes 4, 5
- Effect: begins within minutes, lasts 30-60 minutes 4
- Does NOT lower potassium 4
Step 2: Shift Potassium Intracellularly (15-30 minutes onset)
- Insulin 10 units regular IV with 25g glucose (50 mL D50W) over 15-30 minutes 4
- Nebulized albuterol 10-20 mg over 15 minutes 4
- Sodium bicarbonate 50 mEq IV over 5 minutes (especially if metabolic acidosis present) 4
- Effect lasts 4-6 hours; rebound hyperkalemia can occur 4
Step 3: Eliminate Potassium from Body (Longer-term)
- Loop diuretics (furosemide 40-80 mg IV) if adequate renal function 4
- Newer potassium binders (patiromer, sodium zirconium cyclosilicate) preferred over sodium polystyrene sulfonate 4, 5
- Hemodialysis is most effective for severe hyperkalemia, especially with renal failure 4
Monitoring Requirements
During Administration
- Continuous ECG monitoring (mandatory) 2, 3
- Heart rate every 1-2 minutes 2, 3
- Blood pressure monitoring 3
Post-Administration
- Repeat ionized calcium measurement 4-6 hours after dose 3
- For hyperkalemia, recheck potassium at 1,2,4, and 8 hours to monitor for rebound 4, 8
- Monitor for hypoglycemia if insulin was co-administered 4, 8
Special Populations
Renal Insufficiency
- Calcium supplementation considerations are complex in renal insufficiency 3
- Avoid calcium carbonate as phosphate binder if calcium levels are elevated 1
- For chronic hyperkalemia in patients on RAAS inhibitors, use potassium binders rather than discontinuing cardioprotective medications 4
Pediatric Patients
- Same mg/kg dosing as adults: 50-100 mg/kg for symptomatic hypocalcemia 1, 2
- For life-threatening arrhythmias: 100-200 mg/kg/dose 1, 2
- Use D10W at 200 mg/kg (not D50W) when co-administering glucose with insulin 4
Common Pitfalls to Avoid
- Treating asymptomatic hypocalcemia - this is unnecessary and potentially harmful 1, 3
- Giving calcium without ECG monitoring - bradycardia and arrhythmias can occur suddenly 2, 3
- Mixing calcium with bicarbonate in same line - causes precipitation 1, 2
- Aggressive calcium replacement when phosphate is elevated - risks tissue calcification and obstructive uropathy 1, 3
- Expecting calcium to lower potassium - it only stabilizes cardiac membranes; must combine with potassium-lowering therapies 4
- Using peripheral IV without close monitoring - extravasation causes severe tissue injury 2, 3
- Relying on calcium alone for hyperkalemia - effects last only 30-60 minutes 4
- Giving calcium to digoxin-toxic patients without extreme caution - can precipitate fatal arrhythmias 3
Adverse Effects
Cardiovascular
- Bradycardia (most common, dose-limiting) 2, 3
- Cardiac arrhythmias 3
- Hypotension with rapid administration 3
Local
- Severe skin and soft tissue injury from extravasation 2, 3
- Vein irritation (less than calcium chloride) 3, 4