PSUN09 An Unusual Presentation of Pheochromocytoma with Persistent Hypoglycemia, A Case Report

INTRODUCTION: Pheochromocytoma is a rare chromaffin cells tumor of the adrenal medulla characterized by excessive catecholamines production. It can be manifested by various clinical presentations, ranging from being asymptomatic to having sustained or paroxysmal hypertension, or the classical triad of paroxysmal headache, palpitations, and sweating. It may be sporadic or inherited as part of other familial syndromes, including hereditary paraganglioma syndromes, and multiple endocrine neoplasia 2. This case report shows an unusual presentation of pheochromocytoma in a patient with neurofibromatosis type 1. CASE PRESENTATION: A 27-year-old normotensive woman with a past medical history significant for neurofibromatosis type 1 diagnosed at age 16 was involved in a single-vehicle rollover collision. She experienced a sudden episode of dizziness and presyncope associated with nausea while she was driving. She was found with altered mental status and a serum glucose level of 31 mg/dl (reference value 70-99mg/dL), indicating hypoglycemia which remained persistent after administering a glucose drip. The patient denied any recent febrile illness, previous episodes of dizziness, vertigo, syncope, or known hypoglycemia. Her CT abdomen with intravenous contrast showed a 4.8 cm lobulated heterogeneous mass involving the right adrenal glands concerning for pheochromocytoma. Her laboratory workup revealed HbA1C of 4.9%, serum-free insulin of 6 mcU/mL (reference range <17mcU/mL), C-peptide of 1 ng/mL (reference value 0.5-2 ng/mL), insulin autoantibodies of <0.4 nU/mL (reference value <95 nU/mL), random cortisol of 38.4 mcg/dL (reference value 5-25 mcg/dL), ACTH of <5 pmol/L (reference value 10-60 pmol/L), and a normal cosyntropin stimulation test. Further investigations showed high serum levels of normetanephrine of 8.02 nmol/L (reference range 0-0.89 nmol/L), metanephrines of 0.69 nmol/L (reference range 0-0.49 nmol/L), and chromogranin A of 300 ng/mL (reference range 0-95 ng/mL) which confirmed the diagnosis of pheochromocytoma. CONCLUSION: Hypoglycemia is an unusual presentation of pheochromocytoma, which is usually associated with impaired glucose tolerance and hyperglycemia. Our case shows that pheochromocytoma associated with neurofibromatosis type 1 can present with persistent hypoglycemia. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.