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

Treatment of Hypocalcemia

For severe symptomatic hypocalcemia, administer calcium chloride 10% solution (5-10 mL IV over 2-5 minutes) or calcium gluconate 10% solution (15-30 mL IV over 2-5 minutes), with calcium chloride being the preferred agent due to superior elemental calcium content and faster ionized calcium release. 1, 2, 3

Severity Assessment and Treatment Thresholds

Symptomatic hypocalcemia requires immediate intervention when patients exhibit:

• Paresthesias, Chvostek's or Trousseau's signs 2
• Bronchospasm, laryngospasm, or tetany 2
• Seizures or cardiac arrhythmias 2
• Ionized calcium <0.9 mmol/L (particularly concerning when <0.8 mmol/L due to dysrhythmia risk) 1, 2

Asymptomatic hypocalcemia in stable patients does not require immediate calcium replacement 1

Acute Management: Calcium Replacement

Calcium Chloride vs. Calcium Gluconate

Calcium chloride is superior for several reasons:

• Contains 270 mg elemental calcium per 10 mL of 10% solution (versus only 90 mg in calcium gluconate) 2
• Releases ionized calcium faster, especially critical in patients with liver dysfunction or hypoperfusion 2
• More effective during massive transfusion scenarios 1, 2

Dosing for acute symptomatic hypocalcemia:

• Adults: Calcium chloride 10% solution 5-10 mL IV over 2-5 minutes, or calcium gluconate 10% solution 15-30 mL IV over 2-5 minutes 1
• Pediatric patients: Calcium gluconate 50-100 mg/kg IV administered slowly with ECG monitoring 1
• Maximum infusion rate: Do not exceed 200 mg/minute in adults or 100 mg/minute in pediatric patients 3

Administration Precautions

Critical safety measures:

• Dilute calcium in 5% dextrose or normal saline before administration 3
• Use a secure intravenous line to prevent calcinosis cutis and tissue necrosis from extravasation 3
• Monitor ECG continuously during bolus administration 1, 3
• Never mix calcium with ceftriaxone due to precipitation risk 3
• Do not administer sodium bicarbonate and calcium through the same line 1

Continuous Infusion for Severe or Refractory Hypocalcemia

When single bolus doses are insufficient:

• Initiate continuous infusion at 1-2 mg elemental calcium per kg body weight per hour 2
• Dilute to concentration of 5.8-10 mg/mL in 5% dextrose or normal saline 3
• Target ionized calcium in normal range (1.15-1.36 mmol/L or >1.12 mmol/L) 2
• For moderate-to-severe hypocalcemia (ionized calcium <1 mmol/L), 4 g calcium gluconate infused over 4 hours achieves normalization in 95% of critically ill trauma patients 4

Monitoring during infusion:

• Check ionized calcium every 4-6 hours initially until stable, then twice daily 2
• During continuous infusion, measure every 1-4 hours 3
• Adjust infusion rate based on serial measurements 2

Essential Cofactor Correction

Magnesium deficiency must be corrected first:

• Hypomagnesemia is present in 28% of hypocalcemic ICU patients and prevents calcium correction 2
• Measure serum magnesium immediately in all hypocalcemic patients 2
• Correct magnesium deficiency before expecting full calcium normalization 2

Special Clinical Contexts

Massive Transfusion and Trauma

Hypocalcemia during massive transfusion results from:

• Citrate-mediated chelation of calcium from blood products (each unit contains ~3 g citrate) 1
• Impaired citrate metabolism due to hypoperfusion, hypothermia, or hepatic insufficiency 1, 2
• Colloid infusions (crystalloids do not contribute) 2

Management priorities:

• Monitor and maintain ionized calcium within normal range throughout massive transfusion 1
• Ionized calcium <0.9 mmol/L is associated with coagulopathy, platelet dysfunction, decreased clot strength, and increased mortality 1, 2
• Laboratory coagulation tests may not reflect true impact since samples are citrated then recalcified 1, 2

Tumor Lysis Syndrome

Exercise extreme caution with calcium administration:

• Only treat symptomatic patients 1
• High phosphate levels increase risk of calcium-phosphate precipitation in tissues and obstructive uropathy 1
• Consider renal consultation if phosphate levels are elevated 1

Cardiac Arrest

During cardiac arrest associated with hyperkalemia or hypermagnesemia:

• Calcium chloride 10% solution 5-10 mL or calcium gluconate 10% solution 15-30 mL IV over 2-5 minutes may be considered (Class IIb recommendation) 1

Transition to Maintenance Therapy

Once ionized calcium stabilizes and oral intake is possible:

• Transition to oral calcium carbonate 1-2 g three times daily 2
• Add calcitriol up to 2 μg/day to enhance intestinal calcium absorption 2
• Total elemental calcium intake should not exceed 2,000 mg/day 2
• In CKD patients with PTH >300 pg/mL, active vitamin D sterols are indicated 2

Additional considerations:

• Check 25-hydroxyvitamin D levels; if <30 ng/mL, plan vitamin D supplementation once acute phase is managed 2
• In renal impairment, check PTH levels as secondary hyperparathyroidism may be contributing 2
• Reduce or discontinue phosphate binders based on serum phosphorus levels 2

Critical Monitoring Parameters

Ongoing surveillance:

• Continue monitoring ionized calcium until consistently stable in normal range 2
• Once stable, monitor corrected total calcium and phosphorus at least every 3 months 2
• Be aware that acidosis correction may worsen hypocalcemia (acidosis increases ionized calcium levels) 2

Renal Impairment Dosing

For patients with renal impairment:

• Initiate at the lowest dose of recommended ranges for all age groups 3
• Monitor serum calcium levels every 4 hours 3