How is calcium administered?

How to Administer Calcium

For acute symptomatic hypocalcemia in critically ill patients, administer calcium chloride 20 mg/kg (0.2 mL/kg of 10% solution) IV/IO by slow push for cardiac arrest or infused over 30-60 minutes for other indications, as calcium chloride provides more rapid increases in ionized calcium than calcium gluconate. 1

Emergency/Acute IV Administration

Calcium Chloride (Preferred for Critical Illness)

• Administer calcium chloride 20 mg/kg IV/IO (0.2 mL/kg of 10% solution) for hypocalcemia, hyperkalemia, hypermagnesemia, or calcium channel blocker toxicity 1
• Give by slow push during cardiac arrest; infuse over 30-60 minutes for other indications 1
• Calcium chloride is preferred over calcium gluconate in critically ill children because it results in more rapid increases in ionized calcium concentration 1
• Do not exceed 1 mL/min infusion rate in adults; monitor continuously during administration 2
• Administer through a central venous catheter when possible; extravasation through peripheral IV can cause severe skin and soft tissue injury 1

Calcium Gluconate (Alternative)

• Substitute calcium gluconate 60 mg/kg IV if calcium chloride is unavailable 1
• Dilute to 10-50 mg/mL concentration in 5% dextrose or normal saline before administration 3
• Do not exceed infusion rate of 200 mg/minute in adults or 100 mg/minute in pediatric patients 3
• Monitor ECG continuously during administration; stop if symptomatic bradycardia occurs 1, 3

Critical Safety Considerations for IV Calcium

• Never mix calcium with sodium bicarbonate or administer through the same line 1
• Do not mix with ceftriaxone; concurrent use can form fatal precipitates, especially contraindicated in neonates ≤28 days 3
• Avoid mixing with fluids containing bicarbonate or phosphate; precipitation will occur 3
• Measure serum calcium every 4-6 hours during intermittent infusions and every 1-4 hours during continuous infusion 3
• Use caution in hypocalcemia with elevated phosphate; increased calcium may precipitate calcium phosphate in tissues and cause obstructive uropathy 1

Oral Calcium Supplementation

Formulation Selection

For patients with gastroesophageal reflux disease (GERD) or those taking proton pump inhibitors, prescribe calcium citrate as it does not require gastric acid for absorption and causes less gastrointestinal irritation. 4

• Calcium carbonate provides 40% elemental calcium but requires gastric acid and must be taken with meals 1, 4, 5
• Calcium citrate provides 21% elemental calcium but absorption is independent of meals and gastric acidity 1, 4, 5
• Calcium carbonate is more cost-effective but may cause constipation, bloating, and reflux symptoms 1, 4
• Calcium citrate is preferred for patients on acid-reducing medications (PPIs, H2-blockers) or with achlorhydria 4, 5

Dosing Strategy

• Divide total daily dose into increments of ≤500-600 mg elemental calcium per administration to maximize absorption 1, 4, 5
• Space calcium and iron supplements 2 hours apart as calcium inhibits iron absorption 1
• For pregnancy, administer 1.5-2.0 g elemental calcium daily in divided doses for preeclampsia prevention 1
• After bariatric surgery (RYGB/sleeve gastrectomy), ensure adequate calcium intake with consideration for combined vitamin D and calcium supplementation if PTH is elevated 1

Administration Timing

• Take calcium carbonate with meals to ensure optimal absorption 1, 5
• Calcium citrate can be taken with or without food 1, 4
• Administer vitamin D concurrently as it is essential for optimal calcium absorption 1, 6

Common Pitfalls to Avoid

• Do not use calcium carbonate in patients with significant reflux symptoms as it may exacerbate their condition 4
• Never administer calcium during symptomatic hyperphosphatemia without addressing phosphate levels first; risk of tissue calcification 1
• Avoid total daily calcium intake exceeding 2,000-2,500 mg due to increased risk of kidney stones and potential cardiovascular events 4, 6
• Do not give calcium bicarbonate for hypocalcemia in tumor lysis syndrome if phosphate is elevated; consult nephrology 1
• Verify hyperkalemia with second sample before treating with calcium to rule out factitious elevation from hemolysis 1