What is the treatment for hypocalcaemia (low calcium levels)?

Treatment of Hypocalcaemia

Immediate Management of Severe/Symptomatic Hypocalcaemia

For acute symptomatic hypocalcaemia, administer calcium chloride 10% solution 5-10 mL IV over 2-5 minutes in adults (or 20 mg/kg in children), as calcium chloride is superior to calcium gluconate due to its higher elemental calcium content (270 mg vs. 90 mg per 10 mL) and faster ionized calcium release, especially in patients with liver dysfunction. 1, 2

Acute Calcium Replacement Protocol

Calcium Chloride (Preferred Agent):

• Adults: 5-10 mL of 10% solution IV over 2-5 minutes 1, 2
• Children: 20 mg/kg (0.2 mL/kg) IV/IO 1
• Elemental calcium content: 270 mg per 10 mL 1, 2
• Administer via central line when possible to avoid severe tissue necrosis from extravasation 1
• Continuous cardiac monitoring is mandatory - stop if symptomatic bradycardia occurs 1, 2

Calcium Gluconate (Alternative):

• Adults: 15-30 mL of 10% solution IV over 2-5 minutes 1, 2, 3
• Pediatric: 50-100 mg/kg IV slowly with ECG monitoring 1, 2
• Elemental calcium content: Only 90 mg per 10 mL 1, 2
• Maximum infusion rate: 200 mg/minute in adults, 100 mg/minute in pediatric patients 3
• Use only if calcium chloride unavailable 1, 2

Continuous Infusion for Severe Cases

When ionized calcium <0.9 mmol/L or symptoms persist:

• Initial rate: 1-2 mg elemental calcium/kg/hour 1
• Target: Maintain ionized calcium 1.15-1.36 mmol/L (normal range) 1
• Monitoring: Check ionized calcium every 4-6 hours initially, then twice daily until stable 1
• Dilution: Use 5% dextrose or normal saline to concentration of 5.8-10 mg/mL 3

Critical Cofactor Correction

Hypomagnesaemia MUST be corrected first - hypocalcaemia cannot be fully corrected without adequate magnesium, as magnesium deficiency (present in 28% of hypocalcaemic ICU patients) impairs PTH secretion and causes end-organ PTH resistance. 1, 2

• Administer magnesium sulfate 1-2 g IV bolus immediately for symptomatic patients before calcium replacement 2
• Magnesium acts as cofactor for calcium movement across cell membranes 2
• Calcium supplementation alone will fail if magnesium not corrected 2

Transition to Oral Therapy

Once ionized calcium stabilizes and oral intake possible:

• Calcium carbonate 1-2 g three times daily (preferred oral formulation) 1, 2
• Add calcitriol up to 2 μg/day to enhance intestinal calcium absorption 1, 2
• Total elemental calcium intake should not exceed 2,000 mg/day 1, 2

Context-Specific Management

Massive Transfusion/Trauma Setting

Maintain ionized calcium >0.9 mmol/L minimum (optimal 1.1-1.3 mmol/L) as hypocalcaemia in this context results from citrate-mediated chelation from blood products and is associated with increased mortality, coagulopathy, and cardiovascular dysfunction. 1

• Citrate toxicity worsened by hypothermia, hypoperfusion, hepatic insufficiency 1
• Colloid infusions independently contribute to hypocalcaemia 1
• Critical pitfall: Standard coagulation tests may appear normal despite significant hypocalcaemia-induced coagulopathy because laboratory samples are citrated then recalcified 1
• Monitor ionized calcium continuously during massive transfusion 1, 2

Tumor Lysis Syndrome

Exercise extreme caution - only treat symptomatic patients and consider renal consultation if phosphate elevated, as calcium administration with high phosphate risks calcium-phosphate precipitation in tissues. 1, 2

Chronic Kidney Disease

For CKD patients with corrected calcium <8.5 mg/dL after phosphorus addressed:

• Elemental calcium 1 g/day between meals or bedtime 1
• Vitamin D2 50,000 units orally monthly for 6 months if 25-hydroxyvitamin D <30 ng/mL 1
• Active vitamin D sterols indicated if PTH >100 pg/mL (or 1.5× upper limit normal) 1
• Maintain calcium in low-normal range (8.4-9.5 mg/dL) in stage 5 CKD 2
• Calcium-phosphorus product must remain <55 mg²/dL² 2

Post-Parathyroidectomy

• Measure ionized calcium every 4-6 hours for first 48-72 hours 2
• Initiate calcium gluconate infusion if ionized calcium <0.9 mmol/L 2
• Transition to calcium carbonate 1-2 g TID plus calcitriol up to 2 mcg/day when oral intake possible 2

Critical Safety Considerations

Absolute Contraindications

• Never mix calcium with sodium bicarbonate - causes precipitation 1, 2
• Never administer ceftriaxone with calcium in neonates ≤28 days - forms fatal precipitates 3

Monitoring Requirements

• Ionized calcium every 4-6 hours during acute treatment 1, 3
• Every 1-4 hours during continuous infusion 3
• Continuous ECG monitoring during administration 1, 2, 3
• Measure magnesium, PTH, 25-hydroxyvitamin D, phosphorus 1, 2

Common Pitfalls to Avoid

• Acidosis correction may worsen hypocalcaemia - acidosis increases ionized calcium, so correcting pH unmasks true severity 1
• Avoid overcorrection - can cause iatrogenic hypercalcaemia, renal calculi, renal failure 2
• Phosphate binders may need reduction/discontinuation based on serum phosphorus 1
• Low ionized calcium associated with increased mortality - prompt correction essential 1

Treatment Thresholds

Immediate intervention required when:

• Ionized calcium <0.9 mmol/L (particularly concerning if <0.8 mmol/L due to dysrhythmia risk) 1, 2
• Total corrected calcium ≤7.5 mg/dL 1
• Any symptomatic hypocalcaemia: paresthesias, Chvostek's/Trousseau's signs, bronchospasm, laryngospasm, tetany, seizures, cardiac arrhythmias 1, 2

Asymptomatic hypocalcaemia in stable patients does not require immediate calcium replacement but warrants investigation and monitoring 1

Long-Term Management

For chronic hypocalcaemia:

• Daily calcium and vitamin D supplementation 2, 4
• Regular monitoring of pH-corrected ionized calcium, magnesium, PTH, creatinine 2
• Targeted monitoring during vulnerable periods: perioperative, perinatal, severe illness 2
• Avoid alcohol and carbonated beverages (worsen hypocalcaemia) 2