What are the causes of hypoparathyroidism?

Causes of Hypoparathyroidism

The most common cause of hypoparathyroidism is iatrogenic damage or removal of parathyroid glands during neck surgery, accounting for approximately 75% of all cases. 1, 2

Surgical Causes

• Post-surgical hypoparathyroidism: Most common cause (75% of cases)
  • Total thyroidectomy
  • Parathyroidectomy
  • Radical neck dissection
  • Other anterior neck surgeries

Non-surgical Causes (25% of cases)

Autoimmune Disorders

• Autoimmune hypoparathyroidism
  • Isolated autoimmune hypoparathyroidism
  • As part of autoimmune polyendocrine syndromes 3
  • Antibodies against NACHT leucine-rich-repeat protein 5 and calcium-sensing receptor 3

Genetic Disorders

• DiGeorge syndrome/22q11.2 deletion syndrome: Characterized by the triad of thymic hypoplasia/aplasia, hypoparathyroidism, and congenital heart disease 4
• CHARGE syndrome: Due to mutations in CHD7 gene 4
• Other genetic causes:
  • Mutations in parathyroid development genes
  • X-linked hypoparathyroidism
  • Familial isolated hypoparathyroidism

Infiltrative Disorders

• Metastatic cancer
• Wilson's disease
• Hemochromatosis
• Granulomatous diseases

Mineral Disorders

• Severe hypomagnesemia: Can cause functional hypoparathyroidism 5
• Hypermagnesemia: Can suppress PTH secretion

Radiation-Induced

• External beam radiation to the neck region 4

Rare Causes

• Maternal hyperparathyroidism: Can suppress fetal parathyroid development
• HIV infection
• Riedel's thyroiditis

Clinical Implications and Management Considerations

Hypoparathyroidism leads to hypocalcemia, which can cause serious complications:

• Cardiac dysrhythmias when ionized calcium falls below 0.8 mmol/L 5
• Impaired cardiac contractility and systemic vascular resistance 5
• Seizures and neurological symptoms
• Soft tissue calcifications in kidneys, brain, and other tissues 1

Management Approach

1. Acute management: For severe symptomatic hypocalcemia, administer 1-2g IV calcium gluconate immediately with ECG monitoring 5
2. Chronic management: Conventional therapy with calcium and active vitamin D 6
3. Advanced therapy: Recombinant human PTH(1-84) for cases where conventional therapy is inadequate 7

Important Pitfalls to Avoid

• Failing to distinguish between transient and permanent post-surgical hypoparathyroidism 2
• Overlooking hypomagnesemia as a cause or contributor to hypocalcemia 5
• Inadequate monitoring of calcium, phosphorus, and vitamin D levels during treatment 5
• Excessive calcium supplementation leading to hypercalciuria, renal calculi, and renal failure 5

Patients with hypoparathyroidism require lifelong monitoring and management to prevent complications and maintain quality of life.