SUN-495 Retrospective study of hypercortisolemia in patients with pheochromocytoma

Abstract Disclosure: M. Kometani: None. X. Mai: None. D. Aono: None. S. Konishi: None. S. Karashima: None. T. Yoneda: None. Purpose Pheochromocytoma is a relatively rare form of adrenal hypertension. In recent years, there have been reports of cases of pheochromocytoma combined with primary aldosteronism and Cushing's syndrome, both of which are also derived from the adrenal glands. In general, compared to cases of single diseases or single disorders, cases of complications tend to be more severe, with a higher frequency of electrolyte abnormalities. Furthermore, there have also been a report of cases where pheochromocytoma was found to be associated with abnormal circadian rhythms of cortisol. The aim of this study was to evaluate the prevalence and clinical characteristics of cortisol hypersecretion in patients with pheochromocytoma and to clarify its pathophysiology and diagnostic significance. Methods We retrospectively analyzed data from 23 patients with pheochromocytoma who were diagnosed and treated at our hospital between 2011 and 2022. Results: Serum cortisol levels were evaluated at midnight in 8 of the 23 patients. In all 8 patients, the midnight cortisol level exceeded 50 nmol/L (1.8 µg/dL), with a median of 129.2 nmol/L (63.9-408.3), but there were no apparent signs of Cushing's syndrome. Plasma ACTH levels were within the normal range in 5 cases, but were elevated in 2 cases (88.2 pg/mL, 91.1 pg/mL), and suppressed in 1 case (7.3 pg/mL). The 1 mg dexamethasone suppression test was performed in 4 cases, and in all cases, serum cortisol levels were suppressed to less than 50 nmol/L, and autonomous cortisol secretion was ruled out. Discussion We demonstrated that pheochromocytoma may cause an increase in cortisol levels late at night, and may affect the circadian rhythm of cortisol. Although typical Cushing's symptoms were not observed in all cases, these findings suggest that pheochromocytoma might present with a condition similar to pseudo-CS. Further investigation is needed to determine how it affects blood pressure and blood glucose control. Presentation: Sunday, July 13, 2025