Recurrent hyperthyroidism in an acromegalic patient previously treated with proton beam irradiation: Graves' disease as probable etiology based on follow-up observations.

A 56-year-old woman presented in 1973 with hyperthyroidism and partial anterior pituitary insufficiency. Three years before she had undergone pituitary irradiation for acromegaly and hyperthyroidism, the latter was attributed at the time to excessive TSH secretion because of elevations in plasma TSH. During the present 11/2 years of observation, TSH levels were appropriately low and did not respond to iv TRH when the patient was hyperthyroid. Moreover, they did not rise during treatment, even as the patient became borderline hypothyroid. It is concluded that hyperthyroidism probably has always been due to Graves' disease.