SAT-378 A case of coexisting pheochromocytoma and primary aldosteronism

Abstract T. Battiola: None. C. Watson: None. D.S. Reddy: None. Introduction: While both pheochromocytoma (PHEO) and primary aldosteronism (PA) are recognized causes of resistant hypertension, the coexistence of these two conditions is an exceptionally rare occurrence. Only 15 cases were identified on retrospective review of the literature and a large adrenal mass database from 2000-2020 at Mayo Clinic (1). Providers face unique challenges in diagnosis, management, and counseling of patients with concomitant PHEO and PA. As this case demonstrates, unilateral adrenalectomy often results in persistent PA owing to discordance between PA and PHEO laterality. Case Description: A 72-year-old man with resistant hypertension and a right adrenal mass was referred to Endocrinology after he was found to have an elevated plasma aldosterone concentration (PAC) >20 ng/dL with suppressed renin activity. He denied episodic headaches, sweating, palpitations, or anxiety. In addition to the elevated PAC, he had elevated plasma-free and 24-hour urine-free metanephrines. Adrenal imaging with non-contrasted CT scan showed a heterogenous, 4.0-cm right adrenal mass which was lipid-poor. The left adrenal gland was normal. Adrenal vein sampling (AVS) was considered, but after discussion with the patient we opted to prioritize management of the pheochromocytoma. Adrenergic blockade and volume expansion was difficult to achieve in the face of concomitant PA. He remained hypertensive despite high doses of an alpha blocker and required the addition of a calcium channel blocker and spironolactone. He did not tolerate salt tabs or increased water intake due to volume overload. He was ultimately admitted pre-operatively for volume expansion with IV fluids and underwent laparoscopic right adrenalectomy without complication. Histopathology confirmed pheochromocytoma and repeat 24-hr urine-free metanephrines normalized. His hypertension did not resolve and repeat PAC remains elevated, consistent with persistent PA. Discussion: This case underscores the unique challenges in managing co-existent PHEO and PA and highlights the need for a tailored approach to these patients. For instance, while AVS is the gold standard for detecting the laterality of PA and helps determine if aldosterone excess is due to bilateral adrenal hyperplasia, the safety of this procedure when PHEO has been identified is not clear. Prior to adrenalectomy, patients should be counseled on the possibility of persistent hypertension from discordance of PA and PHEO laterality. Pre-operative preparation should include early initiation of an aldosterone antagonist in addition to adrenergic blockade to optimize blood pressure and improve outcomes. Sources: 1)Mao JJ, Baker JE, Rainey WE, Young WF Jr, Bancos I. Concomitant Pheochromocytoma and Primary Aldosteronism: A Case Series and Literature Review. J Endocr Soc. 2021 Jun 16;5(8):bvab107. doi: 10.1210/jendso/bvab107. PMID: 34258494. Saturday, June 1, 2024