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

Treatment of Hypocalcemia

Administer calcium chloride intravenously to correct hypocalcemia, targeting ionized calcium levels >0.9 mmol/L (normal range 1.1-1.3 mmol/L), with continuous monitoring especially during massive transfusion or critical illness. 1, 2

Immediate Assessment and Monitoring

• Measure ionized calcium, not just total calcium, as ionized calcium is the physiologically active form and total calcium can be misleadingly low due to hypoalbuminemia 1, 2, 3
• Check for symptoms of severe hypocalcemia including paresthesias, Chvostek's and Trousseau's signs, bronchospasm, laryngospasm, tetany, seizures, or cardiac arrhythmias 2
• Monitor ionized calcium every 4-6 hours initially until stable, then twice daily 2, 4
• During massive transfusion or continuous infusion, monitor every 1-4 hours 5, 4
• Always check and correct magnesium first, as hypomagnesemia (present in 28% of hypocalcemic ICU patients) prevents complete calcium correction 2, 6

Acute Intravenous Treatment

Choice of Calcium Agent

Calcium chloride is strongly preferred over calcium gluconate for the following reasons: 1, 2, 5

• Calcium chloride 10% contains 270 mg elemental calcium per 10 mL 2, 5
• Calcium gluconate 10% contains only 90 mg elemental calcium per 10 mL (one-third the amount) 2, 5
• Calcium chloride releases ionized calcium more rapidly, especially critical in liver dysfunction where gluconate metabolism is impaired 2, 5, 7

Dosing Regimens

For symptomatic or severe hypocalcemia (ionized Ca <0.9 mmol/L): 1, 2

• Adults: Calcium chloride 10% solution 5-10 mL IV over 2-5 minutes 2, 6
• Children: 20 mg/kg (0.2 mL/kg) of calcium chloride IV/IO 2
• Alternative if calcium chloride unavailable: Calcium gluconate 10% solution 15-30 mL IV over 2-5 minutes 2

For continuous infusion in severe cases: 2

• Initial rate: 1-2 mg elemental calcium per kg body weight per hour 2
• Adjust based on serial ionized calcium measurements to maintain levels in normal range 2

During massive transfusion: 5

• Administer 1 gram calcium chloride per liter of citrated blood products transfused 5
• Maintain ionized calcium >0.9 mmol/L minimum throughout transfusion 1, 5

Administration Considerations

• Use central venous access when possible to avoid severe tissue necrosis from extravasation 2, 4
• Infuse over 30-60 minutes for non-emergent situations; over 2-5 minutes for cardiac arrest or severe symptoms 2
• Continuous cardiac monitoring is mandatory; stop infusion if symptomatic bradycardia occurs 2, 4
• Never mix calcium with sodium bicarbonate or phosphate-containing fluids as precipitation will occur 2, 4

Critical Context-Specific Considerations

Massive Transfusion and Trauma

• Hypocalcemia results from citrate-mediated chelation of calcium in blood products (especially FFP and platelets) 1, 5
• Citrate metabolism is impaired by hypoperfusion, hypothermia, and hepatic insufficiency—all common in trauma 1, 6
• Colloid infusions (but not crystalloids) independently contribute to hypocalcemia 1, 6
• Low ionized calcium predicts mortality more accurately than fibrinogen, acidosis, or platelet count 1, 6
• Standard coagulation tests may appear normal despite significant hypocalcemia-induced coagulopathy because lab samples are citrated then recalcified before analysis 1, 2

Septic Shock and Critical Illness

• Maintain ionized calcium 1.1-1.3 mmol/L to optimize cardiovascular function and coagulation 2
• Even mild hypocalcemia impairs the coagulation cascade (factors II, VII, IX, X activation) and platelet adhesion 1, 2
• Hypocalcemia is associated with impaired cardiac contractility and decreased systemic vascular resistance 1

Transition to Oral Therapy

Once ionized calcium stabilizes and oral intake is possible: 2, 6

• Calcium carbonate 1-2 grams three times daily 2, 6
• Consider adding calcitriol up to 2 μg/day to enhance intestinal absorption 2, 6
• Total elemental calcium intake should not exceed 2,000 mg/day 2, 6
• Monitor corrected total calcium and phosphorus at least every 3 months 2

Essential Cofactor Correction

Magnesium deficiency must be corrected first: 2, 6

• Measure serum magnesium immediately in all hypocalcemic patients 2
• Administer IV magnesium sulfate for replacement 2
• Hypocalcemia cannot be fully corrected without adequate magnesium 2, 6

Critical Pitfalls to Avoid

• Do not rely on adjusted/corrected total calcium in ICU settings—it has only 78% sensitivity and 63% specificity for predicting low ionized calcium 3
• Do not ignore mild hypocalcemia in critically ill patients, as it impairs coagulation and cardiovascular function even when lab coagulation tests appear normal 1, 2
• Avoid calcium administration with beta-adrenergic agonists when possible, as calcium frequently impairs their cardiovascular actions 2
• Do not overcorrect—avoid severe hypercalcemia (ionized calcium >twice upper limit of normal) 2
• Be aware that correcting acidosis may worsen hypocalcemia, as acidosis increases ionized calcium levels 2

Prognostic Implications

• Hypocalcemia on admission is associated with increased mortality, need for massive transfusion, platelet dysfunction, decreased clot strength, and coagulopathy 1, 6, 5
• Severely hypocalcemic patients who fail to normalize ionized calcium by day 4 have double the mortality (38% vs 19%) 3
• However, calcium supplementation has not been definitively shown to reduce mortality in critically ill patients, though severe hypocalcemia should still be corrected based on physiologic rationale 1, 8, 3
• Most hypocalcemia normalizes within 4 days without supplementation in many patients 3