Primary Hyperparathyroidism

Background and Epidemiology

  • Third most common endocrine disorder (prevalence of between 1 and 20 per 1000 and incidence of around 27-30 per 100,000/year)
  • More common with age, post-menopausal women and with thiazide diuretic use

Aetiology

  • The majority is caused by a single parathyroid adenoma (85%). Multiple adenoma / multiple parathyroid gland involve accounts for most of the remainder.  Rarely can parathyroid cancer cause hyperparathyroidism (<1%)
    • Inferior parathyroids more commonly involved than superior
    • Ectopic glands may also cause hyperparathyroidism in up to 15% of cases (most common in the mediastinum (thymus), oesophagus, thyroid, or jaw)
  • Familial cases can occur as part of multiple endocrine neoplasia syndromes (MEN 1 or MEN 2a)

Clinical Presentation

  • Majority are asymptomatic (incidental diagnosis)
  • Bones, stones, groans and moans
    • Bone pain/pathological fractures (osteopenia)
    • Renal stone disease (most common presentation)
    • Groans
      • Muscle weakness (proximal myopathy), fatigue
      • Abdominal pain, anorexia, nausea, vomiting, constipation, dyspepsia, acute pancreatitis
    • Moans
      • Depression
      • Difficulty concentrating, lethargy, fatigue
  • Rarely presents with cardiac abnormalities e.g. hypertension, short QT interval

Investigation 

see hypercalcaemia

  • Investigation of renal stone disease (i.e. imaging)
  • Bone imaging (DEXA)
  • Parathyroid imaging (Technetium scan)

Management

  • For patients with mild, asymptomatic disease, monitoring (annually) is all that is required
  • Indications for removal of the parathyroids (surgery) include:
    • Severe hypercalcaemia (>3mmol/l or >0.25mmol/l above the upper limit of normal); often if it requires treatment
    • Renal stone disease
    • Low bone density
    • Other complications of hypercalcaemia
    • Young patients (<50) with potentially long follow-up
  • Medical treatments e.g. bisphosphonates, HRT/raloxifene +/- Cinacalcet can occasionally be used (more common in secondary hyperparathyroidism e.g. due to renal disease)

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