Adrenocorticotropin levels do not change during early recovery of transsphenoidal surgery for ACTH-secreting pituitary tumors

In patients with ACTH-secreting pituitary tumor the peri-tumoral normal cor ticotrophs were supposed to be suppressed by cronic hypercortisolemia since frequently they develop transient secondary adrenal insufficiency after pi tuitary tumor resection and during early postoperative days. We evaluated t he ACTH dynamics during transsphenoidal surgery in 16 patients with ACTH-se creting pituitary tumors (6 cured by surgery, 8 not cured Gushing's disease patients and 1 cured by surgery and 1 not cured Nelson's syndrome patients ) and tested the hypothesis that in these patients, ACTH secretion from the peri-tumoral normal corticotrophs is inhibited and hence removal of the en tire tumor should result in subtle postoperative reduction in plasma ACTH. Blood samples for ACTH determination were obtained from 14 Gushing's diseas e patients immediately before pituitary gland manipulation and 10, 30, 60, 90, 120, 150 and 300 min after pituitary tumor resection and on postoperati ve day one. In Nelson's syndrome patients the blood sample was obtained onl y after tumor removal. All patients received intravenous hydrocortisone dur ing surgery and on the first postoperative day. Patients were considered cu red by surgery if they presented adrenal insufficiency after hydrocortisone withdrawal. Mechanical pituitary manipulation induced increase in ACTH lev el. In all 14 Gushing's disease patients (cured and not cured), mean plasma ACTH levels were significantly greater 10 min after pituitary tumor resect ion (54.4+12.8 pmol/l) than in the pre- manipulation period (ACTH=26.3+/-5. 3 pmol/l) (p=0.005). In Gushing's disease patients, the ACTH levels did not change significantly until 300 min after pituitary tumor resection either in those 6 patients cured by surgery (at 10 min after pituitary tumor resec tion ACTH was 54.4+12.8 pmol/l for all 14 Gushing's disease patients and at 300 min after tumor removal ACTH was 39.0+/-12.6 pmol/l for cured and 41.3 +/-15.7 pmol/l for not cured Gushing's disease patients). The ACTH level al so persisted high until 300 min after complete pituitary tumor resection in one cured patient with Nelson's syndrome. ACTH level does not change in th e early recovery period after ACTH-secreting pituitary tumor, even in those cured patients, and probably peri-tumoral normal corticotrophs are not com pletely suppressed by cronic hypercortisolemia (and acute glucocorticoid ad ministration) when these patients are under intense stress, like transsphen oidal surgery. Mechanical pituitary manipulation may induce ACTH release in patients with ACTH-secreting pituitary tumors but probably does not interf ere in the maintenance of high ACTH-levels during the early postoperative p eriod, since ACTH half-life is only 8-15 min. In patients with ACTH-secreti ng pituitary tumors, the behavior of the human hypothalamic-pituitary-adren al system during transsphenoidal surgery does not conform to the specificat ions of a negative feedback mechanism. (C) 2001, Editrice Kurtis.