What is the initial treatment for hypocalcemia (low calcium levels) in the Emergency Room (ER)?

Emergency Room Treatment of Hypocalcemia

For symptomatic or severe hypocalcemia (ionized calcium <0.9 mmol/L or total calcium <1.9 mmol/L), immediately administer intravenous calcium chloride 10% solution 5-10 mL (or 20 mg/kg in children) over 2-5 minutes with continuous cardiac monitoring, followed by a continuous infusion to maintain ionized calcium >0.9 mmol/L. 1, 2

Immediate Assessment and Severity Stratification

Severe hypocalcemia requires immediate intervention when:

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

Asymptomatic hypocalcemia in stable patients does not require immediate calcium replacement 2

Initial Calcium Bolus Administration

Agent Selection

Calcium chloride 10% is the preferred agent over calcium gluconate because: 1, 2

• Delivers 270 mg elemental calcium per 10 mL vs. only 90 mg in calcium gluconate 2
• Produces more rapid increase in ionized calcium concentration 1, 2
• Superior in patients with liver dysfunction, hypothermia, or shock states where citrate metabolism is impaired 2

Dosing for Acute Symptomatic Hypocalcemia

Adults: 2

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

Pediatric patients: 1, 2

• Calcium chloride: 20 mg/kg (0.2 mL/kg of 10% solution) IV/IO
• Alternative: Calcium gluconate 50-100 mg/kg IV with ECG monitoring

Administration Route and Monitoring

• Administer via central venous access when possible to avoid severe tissue injury from extravasation 1, 2
• For cardiac arrest: give as slow bolus (push) 1
• For other indications: infuse over 30-60 minutes 1
• Mandatory continuous cardiac monitoring—stop infusion immediately if symptomatic bradycardia occurs 1, 2

Continuous Calcium Infusion

After initial bolus, initiate continuous infusion at 1-2 mg elemental calcium/kg/hour to maintain ionized calcium in normal range (1.15-1.36 mmol/L): 2

Preparation: 2, 3

• Dilute 100 mL of 10% calcium gluconate (10 vials = 22 mmol calcium) in 1 L normal saline or 5% dextrose
• Infuse at 50-100 mL/hour
• Adjust rate based on serial ionized calcium measurements

Monitoring frequency: 2

• Every 4-6 hours initially until stable
• Then twice daily once stabilized
• During massive transfusion: monitor continuously

Target ionized calcium levels: 2

• Minimum: >0.9 mmol/L to prevent cardiac dysrhythmias and coagulopathy
• Optimal: 1.1-1.3 mmol/L (normal range)

Critical Cofactor Correction

Check and correct magnesium deficiency immediately—hypocalcemia cannot be fully corrected without adequate magnesium, as hypomagnesemia is present in 28% of hypocalcemic ICU patients. 2 Administer IV magnesium sulfate for replacement before expecting full calcium normalization. 2

Context-Specific Considerations

Massive Transfusion/Trauma

• Hypocalcemia results from citrate-mediated chelation from blood products (especially FFP and platelets) 2
• Exacerbated by hypothermia, hypoperfusion, or hepatic insufficiency impairing citrate metabolism 2
• Colloid infusions independently contribute to hypocalcemia beyond citrate toxicity 2
• Maintain ionized calcium >0.9 mmol/L throughout massive transfusion 2

Tumor Lysis Syndrome

• Exercise extreme caution—only treat symptomatic patients 2
• Consider renal consultation if phosphate levels are elevated 2

Cardiac Arrest with Hyperkalemia/Hypermagnesemia

• Consider calcium chloride 10% 5-10 mL or calcium gluconate 10% 15-30 mL IV over 2-5 minutes (Class IIb recommendation) 2

Critical Pitfalls to Avoid

• Do not mix calcium with sodium bicarbonate—causes precipitation 1, 2
• Do not ignore mild hypocalcemia in critically ill patients—impairs coagulation cascade (factors II, VII, IX, X) and platelet adhesion 2
• Standard coagulation tests may appear normal despite significant hypocalcemia-induced coagulopathy because laboratory samples are citrated then recalcified before analysis 2
• Avoid overcorrection—severe hypercalcemia can cause renal calculi and renal failure 2
• Do not administer calcium with beta-adrenergic agonists when possible—calcium impairs their cardiovascular actions 2

Transition to Oral Therapy

When ionized calcium stabilizes and oral intake is possible: 2

• Calcium carbonate 1-2 g three times daily
• Consider adding calcitriol up to 2 μg/day to enhance intestinal calcium absorption
• Total elemental calcium intake should not exceed 2,000 mg/day
• Check 25-hydroxyvitamin D levels—if <30 ng/mL, add vitamin D supplementation

Additional Workup During Stabilization

• Measure serum magnesium immediately 2
• Check PTH levels, especially in patients with renal impairment 2
• Assess 25-hydroxyvitamin D levels 2
• Monitor serum phosphorus 2