Hyperparathyroidism 1

Alternative Names

  • HRPT1
  • Hyperparathyroidism, Familial Isolated Primary
  • FIHP
  • Parathyroid Adenoma, Familial
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WHO-ICD-10 version:2010

Endocrine, nutritional and metabolic diseases

Disorders of other endocrine glands

OMIM Number

145000

Mode of Inheritance

Autosomal dominant

Gene Map Locus

1q31.2

Description

The parathyroid glands are a group of four small endocrine glands that secrete the parathyroid hormone, which regulates the amount of calcium in the blood. Familial isolated hyperparathyroidism (FIHP) is an inherited condition characterized by overactivity of the parathyroid glands. Thus, the condition is characterized by release of excess parathyroid hormone, resulting in hypercalcemia. Primary hyperparathyroidism may result from tumors in the parathyroid; either a parathyroid hyperplasia, or from a parathyroid adenoma or carcinoma. Hyperparathyroidism has a relatively high prevalence of 3 per 1,000. However, about 90% of these cases are non-familial in nature. The condition is hereditary in only about 10% of cases of hyperparathyroidism. Disruption of the normal calcium balance results in typical signs and symptoms of the condition, which include formation of kidney stones, nausea, vomiting, hypertension, weakness, and fatigue. The release of calcium into the blood streams is accompanied by a parallel removal of calcium from the bones, leaving the bones thin and resulting in osteoporosis.

Diagnosis is based on evaluating the clinical and biochemical findings. Molecular genetic testing is also now available for the diagnosis of FIHP. The treatment of choice is parathyroid surgery, either subtotal or limited, depending upon the glandular involvement. Medications can be used for the treatment of severe hypercalcemia secondary to primary hyperparathyroidism in individuals who are unable to undergo parathyroidectomy and for the treatment of parathyroid carcinoma-related hypercalcemia. Lifelong follow-up is important for patients once diagnosed with parahyperthyroidism. These surveillance strategies include annual serum testing for biochemical evidence of hyperparathyroidism, and dental imaging at least every five years, renal ultrasound examination at least every five years, and annual pelvic ultrasound examination and regular gynecologic care for women.

Familial isolated primary hyperparathyroidism (FIHP) is an autosomal dominant disorder. At least three loci have been identified with this condition. PHOAR1 is caused by homozygous mutations in the CDC73 (Cell Division Cycle Protein 73). This gene provides instructions for making the parafibromin protein, which is thought to act as a tumor suppressor. CDC73 gene mutations that cause familial isolated hyperparathyroidism likely result in decreased activity of the parafibromin protein. The loss of parafibromin's tumor suppressor function can lead to the development of parathyroid adenoma or, rarely, parathyroid carcinoma. Mutations in this gene are also responsible for the Hyperparathyroidism-Jaw Tumor Syndrome (HPT-JT).

Molecular Genetics

Familial isolated primary hyperparathyroidism (FIHP) is an autosomal dominant disorder. At least three loci have been identified with this condition. PHOAR1 is caused by homozygous mutations in the CDC73 (Cell Division Cycle Protein 73). This gene provides instructions for making the parafibromin protein, which is thought to act as a tumor suppressor. CDC73 gene mutations that cause familial isolated hyperparathyroidism likely result in decreased activity of the parafibromin protein. The loss of parafibromin's tumor suppressor function can lead to the development of parathyroid adenoma or, rarely, parathyroid carcinoma. Mutations in this gene are also responsible for the Hyperparathyroidism-Jaw Tumor Syndrome (HPT-JT).

Epidemiology in the Arab World

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Other Reports

Kuwait

Hadad (1992) studied 18 patients with Primary Hyperparathyroidism. Serum urate levels and blood pressures were higher in the patient group as compared to age and sex matched controls. Hadad (1992) suggested paying more attention to blood pressure, serum urate and renal function in patients with primary hyperparathyroidism.

[Hadad JF. Hyperuricemia and hypertension in primary hyperparathyroidism. Med Princ Pract. 1992; 3(2):118-22.]

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