SUN-499 Metyrosine: An Unconventional Approach to Managing a Pheochromocytoma

Abstract Disclosure: A.K. Fernando: None. M. Ahmad: None. K.E. Criner: None. Background: Pheochromocytoma is a rare tumor arising from chromaffin cells of the adrenal medulla and carries a high incidence of cardiovascular complications. At least one-third of patients with pheochromocytoma have germline mutations associated with various genetic syndromes. Surgical resection is the preferred choice of therapy. Optimization of hemodynamics prior to surgery is essential to reduce intra operative morbidity. Standard practice includes the addition and titration of alpha and beta adrenergic blockade +/- calcium channel blockade. We present a case of non-metastatic pheochromocytoma managed with metyrosine peri operatively. Case report: A 23-year-old African American female with past medical history of hypertension presented to the ED with headache, nausea vomiting and hypertensive emergency. Blood pressure and heart rate were 217/165 mm/Hg and 120 beats per minute respectively. CT head showed a small volume subarachnoid hemorrhage. Intravenous clevidipine was initiated for blood pressure control. Labs remarkable for significantly elevated serum metanephrines 60 pg/mL (<=57), normetanephrine 13,743 pg/mL (<=148) and chromogranin 1365 ng/mL (<311). CT abdomen showed a 6.6 cm well-circumscribed highly vascularized left suprarenal mass confirming a diagnosis of pheochromocytoma. She was transitioned from clevidipine to doxazosin which was up titrated to achieve a target blood pressure of <130/80 mmHg while supine and >90 mmHg standing to induce orthostasis. She then was started on beta and calcium channel blockade and a high sodium diet (3-5 g/day). A Ga-68 dotatate PET/CT was negative for metastasis. Metyrosine was initiated 5 days before surgery. She successfully underwent a laparoscopic left adrenalectomy with minimum intra operative hemodynamic variation and no post operative complications. Discussion: Surgical intervention, although curative in most cases, carries a significant risk of intra operative complications related to catecholamines released during surgical manipulation. Intra operative hemodynamic instability is an independent risk factor associated with post operative morbidity. Metyrosine is a tyrosine hydroxylase inhibitor that blocks the conversion of tyrosine to 3,4 dihydroxyphenylalanine. The use of metyrosine has been linked to improvement of symptoms related to catecholamines, better intra operative hemodynamics, lower rates of intra operative vasopressor use and improved surgical outcomes. Our patient was started on metyrosine due to size of tumor and degree of elevation of catecholamines. The dose was gradually increased to 4 g/day with fatigue as the only side effect. She was seen 1 month post-surgery with normal ambulatory blood pressures. This case favors the safe use of metyrosine in the peri operative management of pheochromocytoma and should be considered for patients with an elevated risk of surgical complications. Presentation: Sunday, July 13, 2025