Hypercalcaemia

  • Parathyroid glands derived from pharyngeal pouches

  • Pouch III - Inferior parathyroid glands

  • Pouch IV - Superior parathyroid glands

  • Abnormalities of position and number of glands common

  • 5% of population have less than four glands

  • 25% have supernumerary glands often in aberrant positions (e.g. thymus)

Pharyngeal embryology

Parathyroid physiology

  • Parathyroid hormone = 84 amino-acid protein   (MW = 9500)

  • Has half life measured in minutes

  • Broken down to C and N terminal fragments which remain biologically active

  • Acts on cell membrane receptors increasing cAMP

  • In bone - increases turnover and Ca release

  • In kidney - increases production of 1,25 dihydroxy -Vitamin D3

  • In gut  - increases Ca absorption

Causes of hypercalcaemia

  • Primary hyperparathyroidism

  • Malignancy

  • Granulomatous disease

    • Sarcoidosis

    • Tuberculosis

  • Drugs

    • Thiazide diuretics

    • Vitamin D toxicity

    • Lithium

    • Milk alkali syndrome

  • Familial hypercalciuric hypercalcaemia

  • Endocrine

    • Thyrotoxicosis

    • Adrenal crisis

  • Immobilisation

  • Renal Failure

  • Aluminum intoxication

Bibliography

Heys S D,  Smith I C,  Eremin O.  Hypercalcaemia in patients with cancer - aetiology and treatment.  Eur J Surg Oncol 1998;  24:  139-142.

Roche N A,  Young A E.  The role of surgery in mild hyperparathyroidism in the elderly.  Br J Surg 2000;  87:  1640-1649.
 
 

Last updated: 05 January 2008

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