What causes primary hyperparathyroidism?

Updated: Dec 24, 2020
  • Author: Lawrence Kim, MD, FACS, FACE; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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In approximately 85% of cases, primary hyperparathyroidism is caused by a single adenoma. In 15% of cases, multiple glands are involved (ie, either multiple adenomas or hyperplasia). [2] Rarely, primary hyperparathyroidism is caused by parathyroid carcinoma. The etiology of adenomas or hyperplasia remains unknown in most cases. Familial cases can occur as either part of the multiple endocrine neoplasia syndromes (MEN 1 or MEN 2a), hyperparathyroid-jaw tumor (HPT-JT) syndrome, or familial isolated hyperparathyroidism (FIHPT). Familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism also belong to this category. The molecular genetic basis of MEN 1 is an inactivating mutation of the MEN1 gene, located on chromosome band 11q13. MEN 2a is caused by a germline mutation of the Ret proto-oncogene on chromosome 10. [3] Germline mutation of HRPT2 localized on chromosome arm 1q is responsible for HPT-JT, while FIHPT is genetically heterogeneous.

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