MON-501 The Role of Cortisol Secretion in Pheochromocytomas: Clinical and Perioperative Implications - A Retrospective Cohort Study

Abstract Disclosure: K. Zawadzka: None. J. Calissendorff: None. E. Rzepka: None. M. Pędziwiatr: None. A. Hubalewska-Dydejczyk: None. H. Falhammar: None. Background: Pheochromocytomas and paragangliomas (PPGLs) are tumours have a considerable metabolic and cardiovascular risk. New findings reveal that patients with pheochromocytomas have elevated plasma glucocorticosteroid concentrations, which significantly decrease after adrenalectomy when compared to individuals with primary hypertension. This study aimed to evaluate the prevalence, clinical implications, and perioperative outcomes of autonomous cortisol secretion in patients with PPGLs. Design: This was a retrospective cohort study conducted across two tertiary endocrinology centres, including patients with PPGLs who underwent adrenalectomy. Methods: Patients were divided based on the 1 mg dexamethasone suppression test (DST) results into suppressive and non-suppressive groups. Data on clinical characteristics, biochemical markers, tumour features, perioperative outcomes, and follow-up were analysed. Results: Among 106 patients, 24.5% exhibited non-suppressive cortisol concentrations post-DST. These patients were older (median age: 66 vs. 56 years, P<0.001), predominantly female (84.6% vs. 48.8%, P=0.001), and presented with larger tumours (median: 5.2 vs. 4.0 cm, P<0.05). Diabetes was more common in the non-suppressive group both before adrenalectomy (50.0% vs. 26.8%, P<0.05) and after (33.3% vs. 12.7%, P<0.05). Non-suppressive patients had higher urinary and plasma metanephrine concentrations and more cardiovascular diseases. Perioperative complications, including blood loss, conversion to open surgery, and prolonged hospital stays, were more frequent in the non-suppressive group (P<0.05). Conclusions: This study demonstrates that one-quarter of patients with PPGLs exhibit autonomous cortisol secretion, associated with larger tumours, higher diabetes prevalence, and increased perioperative risks. Routine DST-based hypercortisolaemia screening may improve preoperative management and offer insights into the impact of cortisol on PPGLs outcomes. Presentation: Monday, July 14, 2025