Causes
The most common cause of primary hyperparathyroidism is a sporadic, single parathyroid adenoma resulting from a clonal mutation (~97%). Less common are parathyroid hyperplasia (~2.5%), parathyroid carcinoma (malignant tumor), and adenomas in more than one gland (together ~0.5%).
Primary hyperparathyroidism is also a feature of several familial endocrine disorders: Multiple endocrine neoplasia type 1 and type 2A (MEN type 1 and MEN type 2A), and familial hyperparathyroidism.
Genetic associations include:
| OMIM | Name | Gene |
|---|---|---|
| 145000 | HRPT1 | MEN1, HRPT2 |
| 145001 | HRPT2 | HRPT2 |
| 610071 | HRPT3 | unknown at 2p13.3-14 |
In all cases, the disease is idiopathic, but is thought to involve inactivation of tumor suppressor genes (Menin gene in MEN1), or involve gain of function mutations (RET proto-oncogene MEN 2a).
Recently, it was demonstrated that liquidators of the Chernobyl power plant are faced with a substantial risk of primary hyperparathyroidism, possibly caused by radioactive strontium isotopes.
Primary hyperparathyroidism can also result from pregnancy. It is apparently very rare, with only about 110 cases have so far been reported in world literature, but this is probably a considerable underestimate of its actual prevalence in pregnant women.
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