SAT311 A Time And Place For Metyrosine: Successful Treatment Of A Pheochromocytoma Presenting With Hypotension And Multisystem Organ Failure

Disclosure: R. Shafiq: None. J. Giordano: None. Pheochromocytomas are rare neuroendocrine catecholamine-secreting tumors. The surgical excision of pheochromocytoma is definitive management which requires presurgical preparation with an alpha blocker, beta blocker, and sometimes metyrosine to reduce perioperative hemodynamic instability. We present a case of pheochromocytoma complicated with acute on chronic renal failure and acute on chronic heart failure with hypotension requiring metyrosine in presurgical preparation due to hypotension and intolerance to alpha-blocker with successful surgical excision of the tumor. Case: 67 yo M admitted for acute on chronic heart failure and acute on chronic renal failure. He was noted to have an incidental right adrenal mass of 4.3 x 4.5 cm on the CT chest. He denied any prior history of hypertension, episodes of flushing, sweating, palpitations, headaches, or any family history of adrenal malignancies. His labs were consistent with significantly elevated plasma metanephrines to 4.5 nmol/L (normal range < 0.5 nmol/L) and normetanephrine 36 nmol/L (normal range < 0.9 nmol/L). Levels were repeated with slight worsening of metanephrines to 5.6 and normetanephrine to 42. He was hypotensive on presentation initially on milrinone drip that was slowly tapered off. His echo on admission showed left ventricle global hypokinesis with EF 25-30%. He had a worsening renal function on admission and required a few dialysis sessions before being referred to our hospital. He had an MRI adrenal done w/o contrast in the setting of renal failure with a heterogenous mass concerning for pheochromocytoma. PET CT was done which was negative for metastatic disease. Due to strong suspicion of uncontrolled pheochromocytoma as a cause of his heart failure and acute on chronic renal failure, the team and patient opted for unilateral adrenalectomy. He was started on metyrosine pre-surgically as he could not tolerate alpha blockade due to hypotension. His metanephrine levels improved from 5.6 to 1.8 and normetanephrine from 43 to 15 with metyrosine prior to surgery. He had a successful right adrenalectomy and pathology confirmed pheochromocytoma. Of note, he had a history of diabetes with uncontrolled hyperglycemia during admission. Hyperglycemia resolved after adrenalectomy. His plasma metanephrine levels normalized post-adrenalectomy and remained normal on the follow-up visit. Conclusion: Preoperative medical stabilization is a crucial step before surgical resection of pheochromocytoma that traditionally includes an alpha blocker followed by a beta-blocking agent to reduce intra-operative hypertensive crisis. Metyrosine is an often-overlooked agent due to cost, however, should remain in our armamentarium for pheochromocytoma crisis complicated with hypotension when the patient is unable to tolerate an alpha-blocking agent. Presentation: Saturday, June 17, 2023