Hypoparathyroidism

Hypoparathyroidism results from reduced secretion of parathyroid hormone by the parathyroid glands. It results in hypocalcaemia.

Epidemiology

Hypoparathyroidism has an estimated prevalance 37 per 100,000 person-years and incidence of 0.8 per 100 000 person-years. It carries no increased risk of mortality. The majority of cases are due to complications from anterior neck surgery.⁴

Clinical presentation

• tetany: peripheral paresthaesia, carpopedal spasm, seizures
• emotional lability, depression and anxiety, psychosis
• short stature

Pathology

There are a number of causes of hypoparathyroidism ¹:

• iatrogenic, e.g. post parathyroidectomy or thyroidectomy
• congenital absence of the parathyroid glands, which may be syndromic in thymic aplasia, or 22q11.2 deletion syndrome (a.k.a. DiGeorge syndrome)
• familial, e.g. autoimmune polyendocrine syndrome type 1
• idiopathic (probably autoimmune-mediated destruction)

Markers

• parathyroid hormone (PTH) level: low
• serum phosphate level: high
• serum calcium level: low  

Radiographic features

• musculoskeletal ^2,3
  • focal (~25%) and generalised (~10%) osteosclerosis
  • dense metaphyseal bands
  • skull vault thickening ²
  • diffuse idiopathic skeletal hyperostosis-like changes
  • subcutaneous calcification (around shoulders and hips)
• CNS
  • intracranial calcifications: most commonly basal ganglia but also subcortical white matter, corona radiata and thalamus
• head and neck
  • cataract

Differential diagnosis

• Pseudohypoparathyroidism
• Pseudopseudohypoparathyroidism