Hyperparathyroidism

What is Hyperparathyroidism?
Statistics on Hyperparathyroidism
Risk Factors for Hyperparathyroidism
Progression of Hyperparathyroidism
How is Hyperparathyroidism Diagnosed?
Prognosis of Hyperparathyroidism
How is Hyperparathyroidism Treated?
Hyperparathyroidism References
Drugs/Products Associated with Hyperparathyroidism

What is Hyperparathyroidism?

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Hyperparathyroidism is a disease of the Parathyroid glands.

Statistics on Hyperparathyroidism

Mild asymptomatic Hypercalcaemia occurs in about one in 1000 of the population, especially in elderly women and is usually the result of primary hyperparathyroidism. Primary hyperparathyroidism is responsible for 90% of cases of hypercalcaemia.

Risk Factors for Hyperparathyroidism

Excess Parathyroid hormone - primary hyperparathyroidism (80% solitary adenoma, 15% hyperplasia, 4% multiple adenomas, 1.5% primary neoplasia), tertiary hyperparathyroidism (occurs after prolonged secondary hyperparathyroidism when glands act autonomously causing excessive secretion of PTH and hypercalcaemia) ectopic PTH (very rare)

Excess action of vitamin D - self administered vitamin D, sarcoidosis.

Excess calcium intake (milk-alkali syndrome)

Malignant disease (second most common cause) - multiple myeloma, breast cancer, bronchus, thyroid, prostate, renal cell, lymphoma.

Other endocrine disease - Thyrotoxicosis, Addison's disease.

Drugs - thiazide diuretics

Miscellaneous - long-term immobility.

Progression of Hyperparathyroidism

The natural history depends on the cause of the elevated calcium levels. The spectrum ranges from familial hypocalciuric hypercalcaemia which is asymptomatic, not progressive and not associated with any decreased mortality to hypercalcaemia present in the terminal stages of metastatic malignancy. In the situation of hypercalcaemia there is the risk of progresive mineralization of bonem hypercalciuria, nephrocalcinosis and renal failure.In the case of mild primary hyperparathyroidism: the long-term natural history is still not certain. A recent study found no progression of symptoms or worsening of skeletal or renal disease. There is a small risk of hypercalcaemic crisis and so patients should be warned of the hazards of dehydration and immobilization and should known to contact a doctor promptly if they become ill.

How is Hyperparathyroidism Diagnosed?

Urea and Electrolytes - low bicarbonate and raised chloride amd low phosphate (unless co-existant renal failure) support primary hyperparathyroidism.

Alkaline phosphotase raised (part of liver function tests).

Prognosis of Hyperparathyroidism

The outlook varies depending on the specific type of hyperparathyroidism.

How is Hyperparathyroidism Treated?

Treat underlying cause.

Primary hyperparathyroidism - surgical removal of parathyroid adenoma. If parathyroid hyperplasia, then most of all 4 glands are removed. Do calcium levels for at least 14 days post-surgery because of risk of hypocalcaemia.If mild and asymptomatic then conservative treatment is adequate. Recommend high fluid intake to prevent stone formation.Venous sampling or ultrasound is used to locate source of PTH if initial surgery is unsuccessful.Review every 6 months for all patients.

Secondary hyperparathyroidism: deal with underlying cause.Treatment for tertiary hyperparathyroidism follows the same lines as primary hyperparathyroidism.Acute emergency (>3.5 mmol/l) - rehydrate with intravenous fluid, after a minimum of intravemous fluids give biphosphonate infusion. Measure urea and electrolytes at least daily. Do not measure serum calcium for at least 48 hours after intitiation of treatment (normalization may take 3-5 days).Prednisolone - may be useful in some cases (myeloma, sarcoidosis and vitamin D excess) but in most cases ineffective.

Hyperparathyroidism References

[1] Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison's Principles of Internal Medicine. 15th Edition. McGraw-Hill. 2001[2] Cotran, Kumar, Collins 6th edition. Robbins Pathologic Basis of Disease. WB Saunders Company. 1999.[3] Hurst JW (Editor-in-chief). Medicine for the practicing physician. 4th edition Appleton and Lange 1996.[4] Kumar P, Clark M. CLINICAL MEDICINE. WB Saunders 2002 Pg 427-430.[5] Longmore M, Wilkinson I, Torok E. OXFORD HANDBOOK OF CLINICAL MEDICINE. Oxford Universtiy Press. 2001