title: Effect of cimetidine on circulating parathyroid hormone in primary hyperparathyroidism.
abstract: In twelve patients with primary hyperparathyroidism the raised parathyroid hormone (PTH) levels consistently returned to normal with cimetidine ("Tagamet"), 300 mg four times a day, orally. As PTH levels returned to normal, signs and symptoms improved. Reduction of hypercalcaemia varied with the time, dose, and route of administration of cimetidine. Whenever cimetidine was discontinued, there was a rebound of PTH levels to approximately twice the initial value, which suggests that cimetidine blocks the synthesis and/or secretion of parathyroid hormone, so that parathyroid hormone or its precursor accumulates in the gland. A solitary parathyroid adenoma has been confirmed surgically in the five patients so far operated on. In all surgical patients the PTH levels were brought to normal by cimetidine preoperatively; these levels were maintained postoperatively. The adenomas were unusually large, firm, and congested; there was no atrophy of the rest of the glands. These last two observations further support our hypothesis that cimetidine blocks the synthesis or release of parathyroid hormone; they also support the concept that in primary hyperparathyroidism the parathyroid adenoma becomes autonomous or there is an abnormal hormone.
mesh_terms: D000236:Adenoma / Q000503:physiopathology; D000284:Administration, Oral; D000368:Aged; D002927:Cimetidine / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006146:Guanidines / Q000494:pharmacology*; D006801:Humans; D006934:Hypercalcemia / Q000188:drug therapy; D006961:Hyperparathyroidism / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000187:drug effects; D010281:Parathyroid Hormone / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010282:Parathyroid Neoplasms / Q000503:physiopathology
chemical_list: D006146:Guanidines; D010281:Parathyroid Hormone; D002927:Cimetidine