Abstract: It is reported that the increase of serum parathyroid hormone （PTH） lever was related to cognitive impairment in patients with primary  and secondary hyperparathyroidism.Parathyroidectomy can obviously improve the cognitive impairment of patients with hyperparathyroidism.The mechanism of cognitive impairment caused by PTH is unclear,which may be due to the regulation of calcium concentration by binding to PTH receptor in brain,resulting in intracellular calcium overload,or to play as vasoactive factor and affect the cerebral blood flow,thereby causing cognitive impairment.