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

Causes and Treatment of Hypocalcemia

Definition and Causes of Hypocalcemia

Hypocalcemia is defined as ionized calcium <0.9 mmol/L or serum total corrected calcium <7.5 mg/dL and requires prompt treatment with calcium supplementation to prevent serious complications. 1

Common causes of hypocalcemia include:

• Hypoparathyroidism (75% surgical, 25% primary) 2
• Vitamin D deficiency 2
• Chronic kidney disease 3
• Magnesium deficiency
• Acute pancreatitis
• Medication-induced (e.g., bisphosphonates, calcimimetics)
• Massive blood transfusion (citrate chelation) 1

Clinical Presentation

Symptoms of hypocalcemia vary based on severity and onset:

• Neuromuscular: Tetany, paresthesias, muscle cramps, seizures 1, 4
• Cardiac: QT prolongation, arrhythmias, hypotension, bradycardia 1
• Neuropsychiatric: Fatigue, irritability, confusion, memory loss 1
• Severe cases: Laryngospasm, seizures, cardiomyopathy 1

Diagnostic Evaluation

Laboratory evaluation should include:

• Ionized calcium (more accurate than total calcium)
• Albumin-corrected total calcium
• Parathyroid hormone (PTH) levels
• Magnesium levels
• Phosphorus levels
• 25-hydroxyvitamin D levels
• Renal function tests 1

Treatment Approach

Acute Symptomatic Hypocalcemia

For severe or symptomatic hypocalcemia, immediate IV calcium administration is required:

1. IV Calcium Options:

   • Calcium gluconate: 10 mL of 10% solution contains 90 mg elemental calcium 1, 5
   • Calcium chloride: 10 mL of 10% solution contains 270 mg elemental calcium (preferred in emergency situations) 1

2. Administration Guidelines:

   • Dilute in 5% dextrose or normal saline 5
   • For bolus administration: Dilute to 10-50 mg/mL 5
   • Administer slowly with ECG monitoring
   • Do not exceed 200 mg/minute in adults or 100 mg/minute in pediatric patients 1, 5
   • For continuous infusion: Dilute to 5.8-10 mg/mL 5

3. Monitoring:

   • Monitor ionized calcium every 4-6 hours during intermittent infusions
   • Monitor every 1-4 hours during continuous infusion 1, 5

Chronic Hypocalcemia Management

For long-term management:

1. Oral Calcium Supplementation:

   • Elemental calcium 1-2 g/day divided into multiple doses 1
   • Common formulations:
     • Calcium carbonate (40% elemental calcium)
     • Calcium citrate (21% elemental calcium) 1

2. Vitamin D Supplementation:

   • Required in most cases of chronic hypocalcemia
   • Dosage depends on underlying cause and severity

3. Special Considerations:

   • CKD patients: Decisions about phosphate-lowering treatment should be based on progressively or persistently elevated serum phosphate 3
   • Calcimimetic therapy: May increase prevalence of hypocalcemia; individualized approach recommended for treatment 3
   • Renal impairment: Start at lowest dose and monitor serum calcium every 4 hours 5

Precautions and Monitoring

1. Drug Interactions:

   • Avoid mixing calcium with phosphate or bicarbonate-containing fluids due to precipitation risk 1
   • Use caution with cardiac glycosides due to risk of arrhythmias 1, 5
   • Do not mix with ceftriaxone (contraindicated in neonates) 5

2. Monitoring Protocol:

   • For acute management: Monitor ionized calcium every 4-6 hours initially
   • For chronic management: Monitor serum calcium every 2-4 weeks initially, then every 3-6 months once stable 1
   • Maintain calcium-phosphorus product <55 mg²/dL 1

3. Dietary Considerations:

   • Total elemental calcium intake should not exceed 2,000 mg/day
   • Avoid alcohol and carbonated beverages, which can worsen hypocalcemia 1

Special Populations

1. Pregnancy: Maternal hypocalcemia increases risk of spontaneous abortion, premature labor, and preeclampsia 1

2. Pediatric Patients:

   • Dosing should be adjusted based on weight and severity
   • Concomitant use of ceftriaxone and calcium is contraindicated in neonates 5

3. Geriatric Patients:

   • Start at lowest dose of recommended range due to higher risk of decreased renal function 5

Complications of Treatment

• Hypercalcemia from overcorrection
• Kidney stones
• Renal failure
• Calcinosis cutis and tissue necrosis if IV calcium extravasates 5

By following these guidelines, hypocalcemia can be effectively managed while minimizing complications and addressing the underlying cause.