Fact-sheet: Hyperparathyroidism


Updated on 04/23/2019 at 9:58 AM

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Definition

Hyperparathyroidism corresponds to overproduction of parathyroid hormone (PTH) by the parathyroid glands.

Three types of hyperparathyroidism (HPT) are classically distinguished:

  • primary hyperparathyroidism: excessive PTH (parathyroid hormone) secretion due to primary and autonomous dysfunction of the parathyroid glands (most often a parathyroid adenoma),
  • secondary hyperparathyroidism: excessive PTH secretion in response to persistent hypocalcemia caused by age-related vitamin D and calcium deficiency (main etiology), more rarely chronic kidney disease or digestive malabsorption
  • tertiary hyperparathyroidism: autonomization of prolonged secondary hyperparathyroidism, with excessive PTH secretion despite resolution of the initial hypocalcemia. It is observed mainly in end-stage chronic kidney disease. On laboratory testing, primary and tertiary hyperparathyroidism are characterized by hypercalcemia, whereas secondary hyperparathyroidism presents with normal or slightly decreased calcemia. PTH is elevated in all cases.

Clinical features

Asymptomatic forms, discovered through routine calcemia testing, account for the majority of cases of primary HPT. Otherwise, urinary and digestive symptoms are the main presenting signs of the disease.

  • The lithiasic form affects young patients. It is secondary to hypercalciuria (> 0.1 mmol/kg/day). It presents with renal colic. Bilateral and symmetric nephrocalcinosis is sometimes noted.
  • The osseous form was defined by the presence of polyarthralgia, mechanical back pain, pathological fractures of the endocrinopathies of long bones, or joint deformities, with rich radiological semiology. Currently, it is mainly a decrease in bone mineral density on bone densitometry that leads to the discovery of primary HPT.
  • As its name suggests, the nonspecific form includes all kinds of peripheral or
    central neurological manifestations, digestive manifestations, or arterial hypertension.

Laboratory findings

  • Elevated or high-normal PTH
  • Hypocalcemia
  • Hyperphosphatemia

Radiography

  • Extra-articular bone erosions and resorption, acro-osteolysis
  • Band-like osteolysis
  • Subperiosteal erosions
  • Juxtacortical erosions
  • Subchondral erosions and resorption:
  • Acromioclavicular
  • Sternoclavicular
  • Sacroiliac
  • Pubic symphysis
  • Bone texture abnormality:
  • Granular osteoporosis of the skull (rather late) microlacunae with condensation
  • Osteosclerosis
  • Paget-like appearance
  • "Sandwich" or "rugby jersey" vertebrae, band-like osteocondensation of the endplates
  • Possible bone demineralization (10%)
  • Erosive enthesopathy
  • Brown tumor (late)
  • Pseudotumoral lesion, +/- expansile

CT

  • Extra-articular bone erosions and resorption, Acro-osteolysis
  • Band-like osteolysis
  • Subperiosteal erosions
  • Juxtacortical erosions
  • Subchondral erosions and resorption:
  • Acromioclavicular
  • Sternoclavicular
  • Sacroiliac
  • Pubic symphysis
  • Bone texture abnormality:
  • Granular osteoporosis of the skull (rather late finding)
  • Microlacunae with condensation
Osteosclerosis
  • Paget-like appearance
  • "Sandwich" or "rugby jersey" vertebrae, Band-like endplate sclerosis
  • Possible bone demineralization (10%)
  • Erosive enthesopathy
  • Brown tumor (late finding)
  • Pseudotumoral lesion, +/- expansile