Hypothalamic Hypopituitarism Following External Radiotherapy for Tumours Distant From the Adenohypophysis

SUMMARY Three cases of panhypopituitarism and five of isolated growth hormone dificiency which occurred following previous external irradiation of tumours distant from the adenohypphysis are described. The hypothalamic pituitary region received between 2800 and 12000 rads in each case, 1‐9 years before endocrine deficiency was recognized. Evidence is presented that th esite of damage is in the region of the hypothalamus rather than the pituitary gland itself. Individuals treated with X‐ray therapy in whom the hypothalamic‐pituitary region is exposed to irradiation would appear to be at risk of developing some degree of delayed hypothalamic‐pituitary dysfunction. Early reports of the effects of external radiotherapy on hypothalamo‐hypophyseal function suggested that the pituitary gland was resistant to damage from irradiation, but that the hypothalamus and adjacent neural tissues were more sensitive (Kelly et al., 1951; Arnold, 1954). Radiotherapy to malignant tumours distant from the pituitary has not been thought to result in endocrine dysfunction even when the hypothalamo‐hypophyseal region was included in the field of irradiation (de Schryver et al., 1973). Only three reports of documented hypopituitarism following external radiotherapy in such circumstances have been recorded (Tan & Kunaratnam, 1966; Larkins & Martin, 1973; et al., 1975). This paper details the endocrine status of eight patients treated by radiotherapy for malignant disease distant from the pituitary, in whom the hypothalamus was also irradiated. Two of these patients have been reported previously (Larkins & Martin, 1973) and all were found to have severe or partial hypopituitarism.