Endocrine Abstracts

Long-term effects of trans-naso-sphenoidal surgery (TNS) and long-acting somatostatin analogs (SSTa) on hypotalamic-pituitary-adrenal (HPA) function have been poorly investigated. Aim of the study was to evaluate over time the integrity of HPA axis in acromegalic patients with baseline preserved adrenal function and treated with one or both available treatments. We selected 23 patients (15F & 8M, age (±S.D.)=46.8±13.7 yrs) with normal (n=19) or subnormal HPA axis not requiring replacement therapy (n=4). In particular, 15 patients well responsive to chronic SSTa therapy (11 previously operated and 4 de novo) were investigated before and during treatment (median=63 months), while 8 patients cured by TNS were studied 2–3 months after surgery and during follow-up (median=100 months). HPA function was studied by morning circulating cortisol and ACTH levels, urinary free cortisol (UFC) and cortisol response to low-doses short Synacthen test (LDSST, 1 mcg). The cut-off for a normal function was a cortisol peak >500 nmol/liter while a peak between 450 and 500 indicated a partial hypoadrenalism. All patients were studied for serum GH and IGF-I, basal thyroid and gonadal function and MRI. Basal cortisol, ACTH and UFC levels did not significantly change over time and remained in the normal range. Considering the cortisol peak after LDSST, 3 patients with subnormal function at baseline developed overt hypoadrenalism (peak <450 nmol/liter), 7 with normal adrenal function developed partial (n=4) or overt hypoadrenalism (n=3), while HPA function remained unchanged in 13. No significant correlations between HPA axis deterioration and GH/IGF-I levels, type of treatment, SSTa formulation, occurrence of other pituitary deficiencies, presence of secondary empty sella, changes in tumor or residual volume were observed. In conclusion, the HPA axis integrity must be carefully monitored over the time in all acromegalic patients, independently from the type of treatment, and not limited to patients undergoing radiotherapy.