SUN-498 - Pheochromocytoma Presenting as Hyperosmolar Hyperglycemic State and Stroke Mimic in A Young Adult

Background
Pheochromocytoma is a rare catecholamine-secreting tumor classically presenting with episodic hypertension, headache, palpitations, and diaphoresis. Severe hyperglycemia and hyperosmolar hyperglycemic state (HHS) are uncommon presenting manifestations, particularly in patients without established diabetes. We describe a young adult presenting with stroke-like symptoms and HHS due to previously undiagnosed pheochromocytoma.

Case Presentation
A 37-year-old African American male with a history of prediabetes (HbA1c 6.1% six months prior), hypertension, hyperlipidemia, and non-obstructive coronary artery disease presented with four days of progressive lethargy, weakness, and lightheadedness, followed by acute-onset slurred speech and right arm weakness. On arrival, vital signs revealed blood pressure 199/135 mmHg and heart rate 117 bpm. Laboratory evaluation demonstrated profound hyperglycemia (glucose 1,252 mg/dL), elevated serum osmolality, minimal ketosis (acetone 0.1), alkalemia (pH 7.50), and a markedly elevated HbA1c of 16.1%. The patient was admitted to the intensive care unit for management of HHS with insulin infusion and aggressive intravenous fluid resuscitation.
Given the rapid deterioration in glycemic control and severe hypertension, further endocrine evaluation was pursued. Plasma free normetanephrine was markedly elevated at 5,165.7 pg/mL and metanephrine at 2,060.6 pg/mL. CT abdomen with IV contrast revealed an 8.4-cm right adrenal mass consistent with pheochromocytoma. Aldosterone, thyroid-stimulating hormone, adrenocorticotropic hormone, and 24-hour cortisol levels were unremarkable.
Management and Outcome
The patient was stabilized with alpha-adrenergic blockade and antihypertensive therapy. Surgical consultation recommended right adrenalectomy following preoperative optimization of blood pressure and glycemic control. Outpatient endocrinology initiated doxazosin with planned dose escalation prior to surgery.

Conclusion
This case highlights pheochromocytoma as a rare but critical cause of HHS and acute neurologic deficits in patients without established diabetes. Rapid progression from prediabetes to extreme hyperglycemia should prompt evaluation for catecholamine-secreting tumors. Early recognition is essential to prevent morbidity and guide definitive surgical management.

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