Treatment of Symptomatic Hypocalcemia
For symptomatic hypocalcemia, administer intravenous calcium chloride as the preferred agent, given at 10 mL of 10% solution (270 mg elemental calcium) for adults, with continuous ECG monitoring during administration. 1
Acute Management: Agent Selection
- Calcium chloride is superior to calcium gluconate for emergency treatment because 10 mL of 10% calcium chloride contains 270 mg elemental calcium compared to only 90 mg in the same volume of calcium gluconate 1, 2
- Calcium gluconate remains an acceptable alternative when calcium chloride is unavailable, administered as 15-30 mL of 10% solution IV over 2-5 minutes 1
- The FDA-approved dosing for calcium gluconate requires dilution to 10-50 mg/mL concentration and administration at rates not exceeding 200 mg/minute in adults or 100 mg/minute in pediatric patients 3
Critical Pre-Treatment Step
- Check and correct hypomagnesemia immediately before calcium administration, as hypocalcemia cannot be adequately treated without correcting magnesium first—hypomagnesemia is present in 28% of hypocalcemic patients 1
- Administer magnesium sulfate 1-2 g IV bolus immediately for patients with concurrent hypomagnesemia, followed by calcium replacement 1
- Hypomagnesemia causes hypocalcemia through two mechanisms: impaired PTH secretion and end-organ resistance to PTH, explaining why calcium supplementation alone fails 1
Administration Protocol
- Dilute calcium prior to administration in 5% dextrose or normal saline to prevent tissue necrosis 1, 3
- Administer via a secure intravenous line to avoid calcinosis cutis and tissue necrosis 1, 3
- Monitor ECG continuously during administration for cardiac arrhythmias, particularly in patients with prolonged QT interval 1, 2
- Measure serum calcium every 4-6 hours during intermittent infusions and every 1-4 hours during continuous infusion 3
Special Clinical Scenarios
Massive Transfusion
- Continuous IV calcium replacement is required during massive transfusion due to citrate-mediated chelation, with each unit of blood products containing approximately 3g of citrate that binds calcium 1
- Citrate metabolism may be impaired by hypoperfusion, hypothermia, and hepatic insufficiency, requiring more aggressive calcium replacement 1
- In patients with liver dysfunction, calcium chloride may be preferable to calcium gluconate due to decreased citrate metabolism 2
Tumor Lysis Syndrome
- Administer calcium gluconate 50-100 mg/kg IV slowly with ECG monitoring 1
- Use extreme caution when phosphate levels are elevated due to risk of calcium phosphate precipitation in tissues 1
Critical Safety Considerations
- Never administer calcium through the same line as sodium bicarbonate 1
- Do not mix calcium with ceftriaxone—concurrent use can lead to fatal ceftriaxone-calcium precipitates, and concomitant use is contraindicated in neonates (28 days or younger) 3
- Avoid over-correction which can lead to iatrogenic hypercalcemia, renal calculi, and renal failure 1, 2
Transition to Chronic Management
- Once acute symptoms resolve, transition to oral calcium carbonate 1-2 g three times daily plus calcitriol up to 2 mcg/day 1
- Daily calcium and vitamin D supplementation is required for chronic hypocalcemia, with total elemental calcium intake not exceeding 2,000 mg/day 1, 2
- For hypoparathyroidism or severe cases, active vitamin D metabolites (calcitriol 0.5 μg daily or alfacalcidol 1 μg daily) may be required 2
- Maintain serum calcium in the low-normal range (8.4-9.5 mg/dL) to minimize hypercalciuria and prevent renal dysfunction 1, 2
Common Pitfalls to Avoid
- Failing to correct hypomagnesemia first will result in treatment failure 1
- Administering calcium too rapidly can cause cardiac arrhythmias—never exceed recommended infusion rates 1, 3
- Using calcium gluconate instead of calcium chloride in emergencies provides only one-third the elemental calcium 1, 2
- Extravasation causes severe tissue necrosis—ensure secure IV access before administration 1, 3