Endocrine function after external pituitary irradiation in patients with secreting and nonsecreting pituitary tumours.
Endocrine function has been assessed in 22 patients with pituitary adenomas treated by external irradiation. Pituitary-adrenal function was determined by the response to corticotrophin, pyrogen, vasopressin, and insulin-induced hypoglycaemia, and the pattern of response was generally similar to that observed in untreated patients. In one patient only, who showed evidence of pituitary-adrenal dysfunction before treatment, plasma cortisol fell into the hypopituitary range after irradiation. This patient was also the only one to develop thyroid insufficiency after radiotherapy. Gonadal function was impaired in many patients before treatment, but two had normal pregnancies after irradiation. In 10 patients with acromegaly, only one patient showed a marked fall in growth-hormone levels after treatment, and in three patients the levels actually rose during the interval after irradiation. One patient with galactorrhoea due to a tumour secreting excessive amounts of prolactin showed no change in the elevated plasma levels of this hormone after treatment. The last patient, with a corticotrophin-secreting tumour following bilateral adrenalectomy for Cushing's syndrome, had greatly elevated plasma levels of corticotrophin which increased further after radiotherapy.