SUN-459 Adrenalectomy reduces the risk of vertebral fractures in patients with adrenal adenoma and mild autonomous cortisol secretion

Disclosure: V. Favero: None. V. Morelli: None. S. Frigerio: None. C. Aresta: None. F. Pugliese: None. A. Salcuni: None. A. Risio: None. C. Eller-Vainicher: None. S. Palmieri: None. E. Cairoli: None. S. Corbetta: None. A. Scillitani: None. G. Mantovani: None. I. Chiodini: None. Objective: . Mild autonomous cortisol secretion (MACS) is associated with increased risk of vertebral fractures (VFx). However, the impact of recovery from MACS on bone health remains unclear. Design: Retrospective Longitudinal Intervention Study (Study 1): A total of 53 patients with MACS were followed for 35.2±18.6 months (mean±SD). Among these, 31 patients underwent surgery (Study 1-GroupA), while 22 patients received conservative treatment (Study 1-GroupB).Prospective Randomized Study (Study 2): Fifty-one outpatients with MACS were randomly assigned to either adrenalectomy (Study 2-GroupA, 21 patients, 67% females, age 63 [56.5-72.5]) or a conservative approach (Study 2-GroupB, 28 patients, 78% females, age 69 [61-73]) and were followed for 24 months. Methods: MACS was diagnosed in patients with adrenal incidentalomas>1 cm and cortisol after 1-mg dexamethasone suppression test (F-1mgDST)≥1.8 µg/dL. At baseline and at the end of the follow-up we assessed: mineral metabolism, bone mineral density (BMD) at the lumbar spine (LS), total hip (TH) and femoral neck (FN) using Dual-energy X-ray Absorptiometry, and clinical and morphometric vertebral fractures (VFx). Results: . Study 1: Study 1-GroupB showed an increased incidence of VFx (n=11) at the end of the follow-up when compared to Study1-GroupA (n=3, p<0.05). In both groups, BMD at LS, FN and TH were similar at baseline and at the end of follow-up. In Study 1-GroupB, a new VFx occurred in 50% of patients, including 2 out of the 5 patients treated with bisphosphonates; in GroupA, 3 patients (9.7%) experienced incident VFx, all having a prevalent VFx at baseline. Study 2: Patients in both groups were comparable for demographic features (age, sex, BMI), adenoma’s size, cortisol secretion parameters (F-1mgDST, urinary free cortisol, ACTH), prevalent VFx and BMD at baseline. After 24 months, in Study 2-GroupA, we observed significant increases in calcium and phosphate levels compared to baseline (p=0.03 and p=0.04, respectively). In Study 2-GroupB, no significant changes were noted when comparing baseline values with those after 24 months. Additionally, at the end of follow up, BMD remained stable across both groups. However, Study 2-GroupB showed a significantly higher incidence (n=7, 25%) of VFx by the end of the follow-up period compared to Study 2-GroupA (n=1, 4.8%, p=0.04). Conclusions: In patients with unilateral adrenal incidentalomas and MACS, adrenalectomy significantly reduces the risk of vertebral fractures. Presentation: Sunday, July 13, 2025