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

Treatment of Hypocalcaemia

For severe symptomatic hypocalcaemia, administer calcium chloride 10% solution 5-10 mL IV over 2-5 minutes with continuous cardiac monitoring, as calcium chloride is superior to calcium gluconate due to faster ionized calcium release, particularly in patients with hepatic dysfunction. 1, 2

Severity Assessment and Treatment Thresholds

Immediate intervention is required when:

• Ionized calcium <0.9 mmol/L, particularly concerning when <0.8 mmol/L due to dysrhythmia risk 1
• Symptomatic hypocalcaemia with paresthesias, Chvostek's or Trousseau's signs, bronchospasm, laryngospasm, tetany, seizures, or cardiac arrhythmias 1
• Total corrected calcium ≤7.5 mg/dL 1

Asymptomatic hypocalcaemia in stable patients does not require immediate calcium replacement. 1

Acute Management: Calcium Replacement

Agent Selection

Calcium chloride is the preferred agent over calcium gluconate because it releases ionized calcium more rapidly and is more effective in patients with liver dysfunction who cannot efficiently metabolize gluconate. 1, 3

• Calcium chloride 10% contains 270 mg elemental calcium per 10 mL 1
• Calcium gluconate 10% contains only 90 mg elemental calcium per 10 mL and should be used only if calcium chloride is unavailable 1, 2

Dosing by Age Group

Adults:

• Calcium chloride 10%: 5-10 mL IV over 2-5 minutes 1, 2
• Calcium gluconate 10%: 15-30 mL IV over 2-5 minutes (if calcium chloride unavailable) 1, 2

Pediatric patients:

• Calcium gluconate 50-100 mg/kg IV administered slowly with ECG monitoring 1
• Calcium chloride: 20 mg/kg (0.2 mL/kg) IV/IO 1

Administration Guidelines

Route and monitoring:

• Use central venous access when possible to avoid severe tissue injury from extravasation 1, 2
• Continuous cardiac monitoring is mandatory; stop infusion if symptomatic bradycardia occurs 1
• Do not exceed infusion rate of 200 mg/minute in adults or 100 mg/minute in pediatric patients 2

Critical drug interaction:

• Never mix calcium with sodium bicarbonate as it causes precipitation 1
• Do not mix with ceftriaxone; concurrent use can form ceftriaxone-calcium precipitates 2

Continuous Infusion for Severe Cases

When single bolus is insufficient, initiate continuous calcium infusion:

• Start at 1-2 mg elemental calcium per kg body weight per hour 1
• Dilute calcium gluconate in 5% dextrose or normal saline to concentration of 5.8-10 mg/mL 2
• Adjust infusion rate based on serial ionized calcium measurements to maintain levels in normal range (1.15-1.36 mmol/L) 1

Essential Cofactor Correction

Hypomagnesaemia must be corrected first, as hypocalcaemia cannot be fully corrected without adequate magnesium. 1, 3

• Measure serum magnesium immediately, as hypomagnesaemia is present in 28% of hypocalcaemic ICU patients 1
• Administer IV magnesium sulfate for replacement 4

Monitoring During Treatment

Ionized calcium monitoring frequency:

• Every 4-6 hours initially during intermittent infusions until stable 1, 2
• Every 1-4 hours during continuous infusion 2
• Once stable, monitor twice daily 1

Additional monitoring:

• Continuous ECG during administration 1, 2
• Serum phosphorus levels 1
• Magnesium levels 1

Context-Specific Considerations

Massive Transfusion/Trauma

Hypocalcaemia in trauma results from citrate-mediated chelation from blood products, worsened by:

• Hypoperfusion, hypothermia, or hepatic insufficiency impairing citrate metabolism 1, 3
• Colloid infusions (but not crystalloids) independently contributing to hypocalcaemia 1, 3

Maintain ionized calcium >0.9 mmol/L minimum during massive transfusion to preserve coagulation and cardiovascular stability. 1, 3

Tumor Lysis Syndrome

Exercise extreme caution with calcium administration; only treat symptomatic patients and consider renal consultation if phosphate levels are elevated. 1

Cardiac Arrest

Consider calcium chloride 10% 5-10 mL or calcium gluconate 10% 15-30 mL IV over 2-5 minutes during cardiac arrest associated with hyperkalaemia or hypermagnesaemia (Class IIb recommendation). 1

Transition to Oral Maintenance Therapy

Once ionized calcium stabilizes and oral intake is possible:

• Calcium carbonate 1-2 g three times daily 1, 3
• Add calcitriol up to 2 μg/day to enhance intestinal calcium absorption 1, 3
• Total elemental calcium intake should not exceed 2,000 mg/day 1, 3

Additional considerations:

• Measure 25-hydroxyvitamin D levels; if <30 ng/mL, plan vitamin D supplementation once acute phase is managed 1
• Check PTH levels in patients with renal impairment 1
• Reduce or discontinue phosphate binders based on serum phosphorus levels 1

Critical Pitfalls to Avoid

Laboratory coagulation tests may appear normal despite significant hypocalcaemia-induced coagulopathy because samples are citrated then recalcified before analysis, masking the true impact of hypocalcaemia. 1

Do not ignore even mild hypocalcaemia in critically ill patients, as it impairs the coagulation cascade (factors II, VII, IX, X activation) and platelet adhesion. 1

Correction of acidosis may worsen hypocalcaemia, as acidosis increases ionized calcium levels. 1

Avoid calcium administration with beta-adrenergic agonists when possible, as calcium frequently impairs their cardiovascular actions. 1, 5

Prognostic Implications

Low ionized calcium on admission is associated with increased mortality, need for massive transfusion, platelet dysfunction, decreased clot strength, and coagulopathy. 1, 3 Prompt correction is essential to support cardiovascular function and coagulation. 1