Hypoparathyroidism

Introduction

• Causes of ↓ PTH release include
  • accidental surgical excision (thyroidectomy)
  • autoimmune destruction of parathyroid glands
  • DiGeorge syndrome 
    • congenital absence of parathyroid glands
  • hypomagnesemia
    • ↓ functional adenylate cyclase leading to ↓ PTH activity
• Can also be caused by resistance of PTH
  • pseudohypoparathyroidism 
    • renal tubules do not respond in presence of PTH
      • aka Albright hereditary osteodystrophy
• AD inheritance

Presentation

• Symptoms
  • tetany (hypocalcemia)
• Physical exam
  • Chvostek’s sign 
    • contraction of facial muscles when tapped rapidly
  • Trousseau’s sign 
    • carpal spasm following occlusion of brachial artery with BP cuff
  • findings unique to pseudohypoparathyroidism (Albright hereditary osteodystrophy)
    • shortened 4th/5th digits
      • Turners syndrome only involves 5th digit
• short stature

Evaluation

• Serology  
  • hypocalcemia
• hyperphosphatemia

Treatment

• Medical
  • calcium + calcitriol (D₃) supplemenation
  • teriparatide
    • recombinant PTH