What is the treatment for hypocalcemia?

Treatment of Hypocalcemia

For symptomatic hypocalcemia, administer calcium chloride 10 mL of 10% solution (270 mg elemental calcium) intravenously with continuous ECG monitoring, as this provides three times more elemental calcium than calcium gluconate and is the preferred agent for immediate correction. 1

Acute Symptomatic Hypocalcemia

Immediate IV Calcium Administration

• Calcium chloride is superior to calcium gluconate because 10 mL of 10% calcium chloride contains 270 mg elemental calcium versus only 90 mg in the same volume of calcium gluconate 1
• Administer slowly while continuously monitoring ECG for cardiac arrhythmias, particularly QT prolongation and ventricular dysrhythmias 1, 2
• Symptoms requiring immediate IV treatment include neuromuscular irritability, tetany, seizures, paresthesias, muscle spasms, cardiac arrhythmias, and prolonged QT interval 2, 3

Special Clinical Scenarios

• In tumor lysis syndrome with symptomatic hypocalcemia: Administer calcium gluconate 50-100 mg/kg IV slowly with ECG monitoring, but use extreme caution when phosphate levels are elevated due to risk of calcium-phosphate precipitation in tissues 1
• In massive transfusion/trauma patients: Monitor ionized calcium levels closely as citrate in blood products binds calcium; citrate metabolism is further impaired by hypoperfusion, hypothermia, and hepatic insufficiency 1
• Post-parathyroidectomy: Initiate calcium gluconate infusion at 1-2 mg elemental calcium per kg body weight per hour if ionized calcium falls below 0.9 mmol/L (1.15-1.36 mmol/L is normal range) 1

Critical Safety Considerations

• Never administer calcium through the same IV line as sodium bicarbonate as this causes precipitation 1
• Avoid calcium administration when phosphate levels are high (>4.6 mg/dL) without first addressing hyperphosphatemia with phosphate binders 1

Chronic Hypocalcemia Management

Oral Supplementation Strategy

• Start with calcium carbonate as the first-line oral agent, providing the highest elemental calcium content per dose 1, 2
• Total elemental calcium intake from all sources (supplements + diet) must not exceed 2,000 mg/day 1
• Elemental calcium from calcium-based phosphate binders should not exceed 1,500 mg/day 1
• Daily vitamin D supplementation is mandatory for all patients with chronic hypocalcemia 1, 2

Active Vitamin D Metabolites

• Reserve calcitriol (hormonally active vitamin D) for severe or refractory cases, typically requiring endocrinologist consultation 2
• Initial calcitriol dosing: 0.5 μg daily in patients >12 months old, or 20-30 ng/kg body weight daily 2
• The combination of calcium and vitamin D is more effective than either agent alone 2

Target Calcium Levels

• Maintain serum calcium in the low-normal range (8.4-9.5 mg/dL or 2.10-2.37 mmol/L) to minimize hypercalciuria and prevent nephrocalcinosis, renal calculi, and renal failure 1, 3
• In CKD stage 5 patients, maintain corrected total serum calcium toward the lower end of normal 1

Essential Concurrent Corrections

Magnesium Replacement

• Hypomagnesemia must be corrected first as it impairs PTH secretion and prevents successful calcium correction regardless of calcium supplementation 1, 2, 4
• Magnesium supplementation is indicated for all patients with documented hypomagnesemia 1

Vitamin D Deficiency

• Correct vitamin D deficiency (25-OH vitamin D <30 ng/mL) with native vitamin D (cholecalciferol or ergocalciferol) supplementation 2

Monitoring Requirements

Acute Phase

• Measure ionized calcium every 4-6 hours for the first 48-72 hours post-parathyroidectomy, then twice daily until stable 1
• Check serum calcium and phosphorus within 1 week after initiating treatment or adjusting doses 1, 4

Chronic Management

• Monitor pH-corrected ionized calcium, magnesium, PTH, and creatinine concentrations regularly 1, 2
• Measure corrected total calcium and phosphorus at least every 3 months during chronic management 1, 2
• Maintain calcium-phosphorus product <55 mg²/dL² to prevent vascular and soft tissue calcification 1, 2

High-Risk Periods Requiring Intensified Monitoring

• Perioperative periods, pregnancy, childbirth, acute illness, surgery, fractures, and infections all precipitate hypocalcemia 2, 4
• Patients with 22q11.2 deletion syndrome (80% lifetime prevalence of hypocalcemia) require heightened surveillance during all biological stress periods 1, 2

Critical Pitfalls to Avoid

Overcorrection

• Avoid iatrogenic hypercalcemia which causes renal calculi, nephrocalcinosis, and renal failure 1, 2, 3
• Discontinue vitamin D therapy if serum calcium exceeds 10.2 mg/dL (2.54 mmol/L) 2

Lifestyle Factors

• Advise patients to avoid alcohol and carbonated beverages (especially colas) as they worsen hypocalcemia 1, 2

CKD-Specific Considerations

• In dialysis patients on calcimimetics (cinacalcet), the 2025 KDIGO Controversies Conference shifted away from permissive hypocalcemia due to risks of severe hypocalcemia (7-9% incidence), including muscle spasms, paresthesia, and myalgia 1
• If serum calcium falls below 7.5 mg/dL in dialysis patients on cinacalcet, withhold the drug until calcium reaches 8 mg/dL, then reinitiate at the next lowest dose 5
• Adjust dialysate calcium concentration based on patient needs: standard 2.5 mEq/L permits calcium-based binder use; up to 3.5 mEq/L can safely transfer calcium into the patient 1

Underlying Cause Identification

Essential Diagnostic Workup

• Measure ionized calcium (most accurate), PTH, magnesium, phosphorus, creatinine, and 25-hydroxyvitamin D levels 4
• Obtain 12-lead ECG to assess for prolonged QT interval when ionized calcium is below 0.8 mmol/L 4
• Check thyroid-stimulating hormone annually in at-risk populations as hypothyroidism is commonly associated 2, 4

Address Root Causes

• Hypoparathyroidism (most common cause, 75% surgical, 25% primary) 6
• Vitamin D deficiency 6
• Chronic kidney disease with impaired vitamin D activation 2