Parathyroid Glands

The parathyroid glands develop from the endoderm: the superior glands from the fourth pharyngeal pouch, and the inferior glands from the third pharyngeal pouch. Parathyroid glands are usually found on the posterior surface of the thyroid gland. Chief cells secrete PTH, which has a half-life of 3 to 6 minutes. Primary HPT is most often asymptomatic and serendipitously found when the serum calcium value is increased on routine testing. The parathyroid glands can be evaluated with US, CT, MRI, or sestamibi scanning. Cervical exploration for primary HPT involves resection of a solitary adenoma in approximately 85% of patients. Injury to the RLN and superior laryngeal nerve does occur.