Management of Hypocalcemia
For acute symptomatic hypocalcemia, administer intravenous calcium chloride 10% solution (10 mL containing 270 mg elemental calcium) immediately with continuous ECG monitoring, as this provides three times more elemental calcium than calcium gluconate and is the preferred agent for rapid correction. 1
Acute Management Based on Severity
Symptomatic Hypocalcemia (Tetany, Seizures, Laryngospasm, Cardiac Arrhythmias)
- Calcium chloride is superior to calcium gluconate because 10 mL of 10% calcium chloride delivers 270 mg elemental calcium versus only 90 mg from the same volume of calcium gluconate 1
- Administer calcium chloride 10% solution 5-10 mL IV over 2-5 minutes while monitoring ECG for arrhythmias 1
- If calcium chloride is unavailable, use calcium gluconate 10% solution 15-30 mL IV over 2-5 minutes as an alternative 1
- Never administer calcium through the same IV line as sodium bicarbonate due to precipitation risk 1
- Monitor ionized calcium levels every 4-6 hours for the first 48-72 hours, then twice daily until stable 1
Special Consideration: Concurrent Hypomagnesemia
- Correct hypomagnesemia first - administer magnesium sulfate 1-2 g IV bolus immediately before calcium replacement 1
- Hypomagnesemia impairs PTH secretion and causes end-organ PTH resistance, making calcium supplementation alone ineffective 1
- For chronic management, provide oral magnesium oxide 12-24 mmol daily 1
Massive Transfusion Protocol
- Monitor ionized calcium levels continuously during massive transfusion 2
- Maintain ionized calcium concentration above 0.9 mmol/l (normal range 1.1-1.3 mmol/l) to preserve coagulation function and cardiovascular stability 2
- Hypocalcemia during transfusion results from citrate in blood products binding calcium, particularly with FFP and platelet transfusions 2
- Citrate metabolism is impaired by hypoperfusion, hypothermia, and hepatic insufficiency - anticipate more severe hypocalcemia in these conditions 2
Chronic Hypocalcemia Management
Oral Calcium Supplementation
- Calcium carbonate is the preferred first-line oral supplement for chronic hypocalcemia 2, 1
- Start with 1-2 g of calcium carbonate three times daily with meals 1
- Total elemental calcium intake should not exceed 2,000 mg/day from all sources (diet plus supplements) 2, 1
- Divided dosing (4 times daily with meals and at bedtime) results in substantially greater absorption than once-daily dosing 3
- Gastric acid is not necessary for calcium carbonate absorption when taken with meals 3
Vitamin D Therapy
- Calcitriol (active vitamin D) is indicated when PTH is elevated or vitamin D metabolism is impaired 4
- For hypoparathyroidism: start calcitriol 0.25 mcg daily in the morning, increase by 0.25 mcg at 2-4 week intervals if needed 4
- Most adults respond to calcitriol doses of 0.5-2 mcg daily 4
- For dialysis patients: start 0.25 mcg daily, increase by 0.25 mcg at 4-8 week intervals; most respond to 0.5-1 mcg daily 4
- Check serum calcium at least twice weekly during dose titration 4
Target Calcium Levels
- Maintain corrected total serum calcium in the low-normal range (8.4-9.5 mg/dL or 2.10-2.37 mmol/L) to minimize hypercalciuria and prevent renal complications 2, 1, 5
- In CKD stage 5, target the lower end of normal range 2
- Keep calcium-phosphorus product below 55 mg²/dL² to prevent vascular calcification 2, 1
Monitoring Requirements
Initial Titration Phase
- Measure serum calcium at least twice weekly during dose adjustments 4
- Monitor ionized calcium, magnesium, PTH, and creatinine regularly 1
- Check 24-hour urinary calcium to detect hypercalciuria 4
Maintenance Phase
- Check serum calcium monthly once stable dose is established 4
- Monitor phosphorus, magnesium, and alkaline phosphatase periodically 4
- Assess for hypercalciuria to prevent nephrocalcinosis 2
Critical Safety Considerations
Avoiding Overcorrection
- Overcorrection causes iatrogenic hypercalcemia, renal calculi, and renal failure 1
- If corrected total calcium exceeds 10.2 mg/dL, immediately reduce or discontinue calcium-based binders and active vitamin D 2
- Hypercalcemia typically resolves in 2-7 days after discontinuing calcitriol 4
- Restart therapy at 0.25 mcg/day less than prior dose once normocalcemia returns 4
High Phosphate Situations
- Use extreme caution with calcium replacement when phosphate levels are elevated due to risk of calcium-phosphate precipitation in tissues 1
- In tumor lysis syndrome with hyperphosphatemia, administer calcium only if severely symptomatic and with intensive monitoring 1
Addressing Underlying Causes
PTH-Mediated Hypocalcemia
- Post-surgical hypoparathyroidism is the most common cause of chronic hypocalcemia 5, 6
- Requires lifelong calcium and calcitriol supplementation 1, 5
- Recombinant human PTH(1-84) is FDA-approved for hypoparathyroidism but reserved for refractory cases due to high cost 6
Non-PTH-Mediated Hypocalcemia
- Vitamin D deficiency: supplement with cholecalciferol or ergocalciferol to achieve 25-hydroxyvitamin D >30 ng/mL before using active vitamin D 1
- CKD patients: individualize approach based on PTH levels and stage of kidney disease 2, 1
- Malabsorption syndromes: may require higher doses of calcium and vitamin D; consider calcium citrate for better absorption in achlorhydria 7
High-Risk Populations Requiring Enhanced Surveillance
22q11.2 Deletion Syndrome
- 80% have lifetime history of hypocalcemia that may arise or recur at any age despite apparent childhood resolution 1
- Provide daily calcium and vitamin D supplementation universally 1
- Avoid alcohol and carbonated beverages (especially colas) as they worsen hypocalcemia 1
- Intensify monitoring during biological stress: surgery, childbirth, infection, fractures 1
Post-Parathyroidectomy Patients
- Initiate calcium gluconate infusion at 1-2 mg elemental calcium/kg/hour if ionized calcium falls below 0.9 mmol/L 1
- Transition to oral calcium carbonate 1-2 g three times daily plus calcitriol up to 2 mcg/day when oral intake possible 1
- Monitor ionized calcium every 4-6 hours initially 1