Pheochromocytoma Secreting Large Quantities of Both Epinephrine and Norepinephrine Presenting with Episodes of Hypotension and Severe Electrolyte Imbalance

Pheochromocytoma is a rare tumor usually arising from the adrenal medulla (strictly speaking, those arising outside the adrenal gland are called paragangliomas). We report a case of pheochromocytoma presenting as orthostatic hypotension and electrolyte imbalance. A 51-year-old woman was admitted because of vomiting and chest pain. She had fluctuating blood pressure (BP) with episodes of orthostatic hypotension. Computed tomography pulmonary angiogram was performed to rule out pulmonary embolism; it showed a clear chest, but an incidental right suprarenal mass. The biochemical analysis supports the diagnosis of pheochromocytoma. Her electrolyte panel revealed persistently low potassium, calcium, and magnesium levels despite aggressive replacement. We speculated that hypotension was mainly due to vasodilatation caused by excess plasma epinephrine and prescribed doxazosin and a nonselective beta-adrenergic blocker which stabilized BP. The right adrenal tumor excised, and postoperatively she remained hemodynamically stable with no hypotensive episode. Laboratory data taken six weeks after surgery show normal 24-hour urine metanephrine and normetanephrine and normal serum magnesium and calcium levels. This case report highlights the variable presentation of pheochromocytoma. We also discuss the probable mechanisms of electrolyte imbalance in our case.