What are the symptoms and treatment of hypocalcemia?

Hypocalcemia: Symptoms and Treatment

Hypocalcemia presents with neuromuscular irritability, tetany, seizures, paresthesias, muscle cramps, tremors, and cardiac arrhythmias, and requires prompt treatment with IV calcium gluconate for severe cases and oral calcium with vitamin D supplementation for chronic management. 1

Symptoms of Hypocalcemia

Hypocalcemia manifests with varying severity depending on the calcium level and rate of decline:

Neurological and Musculoskeletal Symptoms

• Mild symptoms: Circumoral numbness, paresthesias of hands and feet, muscle cramps 2
• Moderate symptoms: Fatigue, irritability, muscle tremors, rigidity 3
• Severe symptoms: Tetany, laryngospasm, focal or generalized tonic muscle cramps, seizures 2

Cardiovascular Symptoms

• QT interval prolongation
• Cardiac arrhythmias (can be life-threatening)
• Hypotension
• Bradycardia 4, 5

Diagnostic Approach

A comprehensive workup should include:

1. Laboratory tests:

   • Serum calcium with albumin correction or ionized calcium (ionized calcium <0.8 mmol/L indicates significant hypocalcemia)
   • Parathyroid hormone (PTH) levels
   • Magnesium and phosphorus levels
   • Vitamin D levels
   • Renal function tests 1

2. Categorization based on PTH levels:

   • High PTH: Suggests secondary hyperparathyroidism (vitamin D deficiency, renal disease, calcium malabsorption)
   • Low/inappropriately normal PTH: Suggests hypoparathyroidism (post-surgical, autoimmune, genetic) 1

Common Causes of Hypocalcemia

1. Hypoparathyroidism:

   • Post-surgical (most common cause)
   • Autoimmune disorders
   • Genetic causes 6

2. Vitamin D disorders:

   • Deficiency
   • Resistance
   • Impaired metabolism 7

3. Medication-induced:

   • Bisphosphonates
   • Anticonvulsants
   • Proton pump inhibitors 1

4. Other causes:

   • Hypomagnesemia (causes functional hypoparathyroidism)
   • Chronic kidney disease
   • Acute pancreatitis
   • Critical illness
   • Massive blood transfusion 1, 2

5. Genetic disorders:

   • 22q11.2 deletion syndrome (affects approximately 60% of children) 3

Treatment Algorithm

Acute Symptomatic Hypocalcemia

1. Immediate intervention:

   • Administer 1-2g IV calcium gluconate (100-200 mg/kg for pediatric patients)
   • Administer slowly with ECG monitoring to prevent cardiac complications 1, 4
   • For transfusion-related hypocalcemia, calcium chloride may be preferred 1

2. Monitor closely:

   • Check serum calcium levels every 4-6 hours during intermittent infusions
   • Check every 1-4 hours during continuous infusions 1

3. Address underlying causes:

   • Correct hypomagnesemia if present (essential before calcium levels will normalize)
   • Treat the primary disorder 1

Chronic Hypocalcemia Management

1. Oral supplementation:

   • Calcium (600 mg/day)
   • Vitamin D3 (400 IU/day) 1
   • Adjust dosage based on serum calcium levels

2. For hypoparathyroidism:

   • Carefully titrate calcium and vitamin D supplementation
   • Maintain serum calcium in low-normal range to minimize hypercalciuria
   • Consider recombinant human PTH(1-84) for selected patients with difficult-to-control hypoparathyroidism 7, 6

3. Special considerations:

   • For patients with renal impairment, start at the lowest recommended dose
   • Monitor serum calcium levels every 4 hours 4
   • In CKD patients, use dialysate calcium concentration between 1.25 and 1.50 mmol/L 1

Prevention of Complications

• Avoid overcorrection of hypocalcemia, which can lead to hypercalcemia, renal calculi, and renal failure 1
• Monitor for complications including hypercalciuria, nephrocalcinosis, and soft tissue calcification 1
• Be aware of drug interactions:
  • Hypercalcemia increases risk of digoxin toxicity
  • Calcium may reduce response to calcium channel blockers 4
• Recognize that hypocalcemia can recur during periods of biological stress (perioperative, acute illness, puberty, pregnancy, decreased oral intake) 3

Special Populations

• Neonates: Concomitant use of ceftriaxone and calcium gluconate is contraindicated in neonates ≤28 days due to risk of fatal outcomes 4
• Pregnant women: Maternal hypocalcemia can result in increased spontaneous abortion, premature labor, and preeclampsia 4
• Elderly: Start at lowest recommended dose due to higher risk of decreased organ function 4

By following this structured approach to diagnosis and management, hypocalcemia can be effectively treated while minimizing complications and addressing the underlying cause.