Responsiveness of growth hormone release in acromegalics after irradiation or hypophysectomy

Effects of X-ray irradiation to the pituitary and transfrontal hypophysectomy were evaluated on the responsiveness of plasma growth hormone (GH) to exogenous stimuli in 8 patients with acromegaly. As exogenous stimuli, arginine, TRH, LH-RH and L-dopa were administered. In 2 out of 3 patients treated with Liniac irradiation, the responsiveness to arginine was essentially unchanged, while in the third patient positive response to arginine disappeared after therapy. Of 2 patients who received a combination of hypophysectomy and Liniac irradiation, the responsiveness to arginine, TRH, LH-RH and L-dopa did not change in 1 patient, but in the other it was observed that negative response to L-dopa became positive after the treatment, remaining the unchanged responsiveness to arginine, TRH, and LH-RH. In 3 hypophysectomized patients, little change in responses to the above 4 stimuli was observed. In summary, out of 22 pairs of responses (pre- and post-therapy) examined 20 were not altered. In 11 pairs of responses (pre- and post-irradiation) particularly, 10 were essentially unchanged. It might be concluded that the responsiveness of GH to exogenous stimuli in acromegalics would not be affected by irradiation or transfrontal hypophysectomy.