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 corticotrophs were supposed to be suppressed by cronic hypercortisolemia since frequently they develop transient secondary adrenal insufficiency after pituitary tumor resection and during early postoperative days. We evaluated the ACTH dynamics during transsphenoidal surgery in 16 patients with ACTH-secreting pituitary tumors (6 cured by surgery, 8 not cured Cushing'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 entire tumor should result in subtle postoperative reduction in plasma ACTH. Blood samples for ACTH determination were obtained from 14 Cushing's disease patients immediately before pituitary gland manipulation and 10, 30, 60, 90, 120, 150 and 300 min after pituitary tumor resection and on postoperative day one. In Nelson's syndrome patients the blood sample was obtained only after tumor removal. All patients received intravenous hydrocortisone during surgery and on the first postoperative day. Patients were considered cured by surgery if they presented adrenal insufficiency after hydrocortisone withdrawal. Mechanical pituitary manipulation induced increase in ACTH level. In all 14 Cushing's disease patients (cured and not cured), mean plasma ACTH levels were significantly greater 10 min after pituitary tumor resection (54.4+/-12.8 pmol/l) than in the premanipulation period (ACTH=26.3+/-5.3 pmol/l) (p=0.005). In Cushing'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 resection ACTH was 54.4+/-12.8 pmol/l for all 14 Cushing'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 Cushing's disease patients). The ACTH level also persisted high until 300 min after complete pituitary tumor resection in one cured patient with Nelson's syndrome. ACTH level does not change in the early recovery period after ACTH-secreting pituitary tumor, even in those cured patients, and probably peri-tumoral normal corticotrophs are not completely suppressed by cronic hypercortisolemia (and acute glucocorticoid administration) when these patients are under intense stress, like transsphenoidal surgery. Mechanical pituitary manipulation may induce ACTH release in patients with ACTH-secreting pituitary tumors but probably does not interfere in the maintenance of high ACTH-levels during the early postoperative period, since ACTH half-life is only 8-15 min. In patients with ACTH-secreting pituitary tumors, the behavior of the human hypothalamic-pituitary-adrenal system during transsphenoidal surgery does not conform to the specifications of a negative feedback mechanism.

Tratamiento médico de los tumores hipofisiarios productores de corticotrofina y tirotrofina / Medical treatment of adrenocorticotrophin and thyrotrophin-secreting pituitary tumors

Se analiza el estado actual del tratamiento médico de los tumores hipofisiarios productores de corticotrofina (ACTH) y tirotrofina (TSH). Se presentan las investigaciones comunicadas por diversos autores en el tratamiento de la enfermedad de Cushing y el síndrome de Nelson con moduladores de la secreción de ACTH, la bromocriptina, la ciproheptadina, la ritanserina, el ácido valproico y la somatostatina. Los resultados positivos cubren un pequeño número de casos. La primera opción de tratamiento de estos tumores es la cirugía seguida de la radioterapia. Cuando no se logra extirpar completamente los tumores, el uso de drogas que actúan inhibiendo la esteroidogénesis suprarrenal constituye una terapia paliativa. Entre estas drogas se cuentan el ketoconazol, la aminoglutetimida, la metopirona, el mitotano y el trilostan, con diversos grados de efectividad y tolerancia. Los pacientes que presentan tumores hipofisiarios productores de TSH han sido tratados con éxito con análogos de la somatostatina de acción prolongada, octreotide y lanreotide SR. Se ha logrado dramática supresión de la TSH y de la subunidad alfa, así como control del hipertiroidismo y disminución del tamaño de los tumores. Estas drogas ofrecen posibilidades de tratamiento médico para los pacientes que no logran control de su enfermedad con la cirugía