A parathyroid growth factor that is related to the fibroblast growth factor family has recently been identified and may be responsible, at least in some patients, for parathyroid hyperplasia related to the MEN type-I syndrome. Other growth factors that may be involved in parathyroid gland hyperplasia presumably exist, but have not yet been identified.
Another factor that has been implicated in the pathophysiology of primary hyperparathyroidism is external irradiation, since there is some evidence that patients with a history of neck irradiation may be predisposed to the condition.
