Autonomous hyperparathyroidism: a possible late complication of neck radiotherapy.

In a series of 170 patients operated on for autonomous hyperparathyroidism (HPT) during a four-year period ending 1974, 24 patients (14%) had, earlier in life, received radiation therapy to the neck region for various benign conditions. Treatment records were traced in 19 cases. The estimates of absorbed dose in the parathyroids ranged from 200 to 3 000 rad. Eighteen patients had their first course of treatment in childhood or early adult life. The diagnosis of HPT was established in these patients 42 years (average) after exposure to radiation. Six patients who were irradiated after the age of 48 had an average time lapse of 12 years before the diagnosis of HPT was made. The occurrence of signs and symptoms related to HPT was similar in exposed and non-exposed patients. The high incidence of previous neck radiotherapy in our series suggests that radiation may be a contributory factor in the development of HPT.