Overview Synthesis made in parafollicular cells (C cells) of thyroid in response to hypercalcemia inferior parathyroid glands derived from the 3rd pharyngeal pouch superior parathyroid glands derived from the 4th pharyngeal pouch parafollicular C cells derived from ultimobranchial body (4th/5th pharyngeal pouch) originally thought to be of neural crest in origin but are now considered to be a derivative of endoderm Function ↓ serum Ca2+ via ↓ bone resorption PTH antagonism not essential in normal Ca2+ homeostasis can be used in management of osteoporosis or hypercalcemia (not first line for either) Pathology medullary carcinoma of the thyroid parafollicular C cells overproduce caltonin creating sheets of cells in an amyloid stroma stains with Congo red associated with MEN 2A and 2B (mutation in RET)