What is the appropriate physician's order for administering calcium gluconate 10% intravenously (initial bolus and continuous infusion) in an adult with symptomatic hypocalcemia?

Calcium Gluconate Infusion Protocol for Symptomatic Hypocalcemia in Adults

For an adult with symptomatic hypocalcemia, administer calcium gluconate 10% as an initial bolus of 1–2 grams (10–20 mL) infused intravenously over 10–20 minutes with continuous ECG monitoring, followed by a continuous infusion of 1–2 mg elemental calcium per kg per hour (approximately 50–100 mL/hour of 10% calcium gluconate for a 70-kg patient), titrated to maintain ionized calcium 1.15–1.36 mmol/L. 1, 2

Initial Bolus Dose

• Administer 1–2 grams of calcium gluconate 10% (10–20 mL) intravenously over 10–20 minutes for symptomatic acute hypocalcemia in adults 1
• For moderate to severe hypocalcemia (ionized calcium <1 mmol/L), use the higher end of this range (2 grams) 1
• Continuous ECG monitoring is mandatory during bolus administration—stop immediately if symptomatic bradycardia occurs or heart rate drops by ≥10 beats per minute 1

Continuous Infusion Protocol

• Start a continuous infusion at 1–2 mg elemental calcium per kg per hour after the initial bolus 2
• For a 70-kg adult, this translates to approximately 50–100 mL/hour of 10% calcium gluconate (since 10 mL of 10% calcium gluconate contains 93 mg elemental calcium) 3
• A practical approach: infuse 4 grams of calcium gluconate (40 mL of 10% solution) over 4 hours (rate of 1 g/hour) for moderate to severe hypocalcemia 4, 5

Monitoring Requirements

• Measure ionized calcium every 4–6 hours during the first 48–72 hours, then twice daily until stable 1, 2
• During continuous infusion, check ionized calcium every 1–4 hours initially to guide titration 3
• Target ionized calcium: 1.15–1.36 mmol/L (normal range) 2
• Minimum acceptable threshold is >0.9 mmol/L to prevent cardiovascular dysfunction and coagulopathy 2

Infusion Rate Titration Algorithm

• If ionized calcium <0.9 mmol/L: increase infusion rate by 25–50% and recheck in 2–4 hours 2
• If ionized calcium 0.9–1.15 mmol/L: continue current rate and recheck in 4–6 hours 2
• If ionized calcium 1.15–1.36 mmol/L: maintain current rate and transition to less frequent monitoring 2
• If ionized calcium >1.36 mmol/L: reduce infusion rate by 50% or discontinue temporarily, recheck in 2–4 hours 2

Vascular Access & Administration Route

• Central venous access is strongly preferred to avoid severe extravasation injury, tissue necrosis, and calcinosis cutis 1, 6
• If only peripheral access is available, ensure the line is secure and monitor the site closely for signs of infiltration 1
• Never administer through the same line as sodium bicarbonate or phosphate-containing fluids—precipitation will occur 1, 3

Critical Pre-Treatment Considerations

Check and Correct Magnesium First

• Measure serum magnesium immediately—hypomagnesemia is present in 28% of hypocalcemic ICU patients and prevents calcium correction 2
• Correct magnesium deficiency before expecting full calcium normalization with IV magnesium sulfate 2

Assess Phosphate Levels

• If serum phosphate is elevated (especially in tumor lysis syndrome), exercise extreme caution with calcium administration 1, 6
• Increased calcium with hyperphosphatemia can precipitate calcium-phosphate crystals in tissues, causing obstructive uropathy 1
• Consider renal consultation before aggressive calcium replacement in this setting 1

Evaluate for Digoxin Use

• Avoid calcium administration in patients on digoxin whenever possible 1
• If absolutely necessary, give slowly in small aliquots with close ECG monitoring to prevent precipitating digoxin toxicity and life-threatening arrhythmias 1

Sample Physician Order Set

For a 70-kg adult with symptomatic hypocalcemia:

1. Calcium gluconate 10% 20 mL (2 grams) IV over 20 minutes with continuous cardiac monitoring 1
2. Then calcium gluconate 10% continuous infusion at 50 mL/hour (adjust based on ionized calcium levels) 2, 3
3. Check ionized calcium, magnesium, phosphate, and albumin STAT 2
4. Recheck ionized calcium in 4 hours, then every 4–6 hours for 48 hours 2
5. Target ionized calcium 1.15–1.36 mmol/L 2
6. Stop infusion immediately if heart rate drops ≥10 bpm or symptomatic bradycardia occurs 1
7. Administer via central line if available; if peripheral, ensure secure IV and monitor site closely 1, 6
8. Do NOT mix with bicarbonate or phosphate-containing solutions 1, 3

Transition to Oral Therapy

• When ionized calcium stabilizes and oral intake is possible, transition to oral calcium carbonate 1–2 grams three times daily 2
• Consider adding calcitriol up to 2 μg/day to enhance intestinal calcium absorption 2
• Gradually reduce the infusion rate as oral therapy takes effect, monitoring ionized calcium every 6–12 hours during the transition 2

Common Pitfalls to Avoid

• Do not treat asymptomatic hypocalcemia—even in tumor lysis syndrome, calcium replacement is unnecessary and potentially harmful 1
• Do not use fixed calcium-to-blood-product ratios—always titrate to measured ionized calcium levels 2
• Do not ignore magnesium deficiency—hypocalcemia cannot be fully corrected without adequate magnesium 2
• Do not infuse rapidly—this causes cardiac arrhythmias, hypotension, and symptomatic bradycardia 1
• Do not rely on total serum calcium alone—ionized calcium is the physiologically active form and must be monitored 2