The hypertension in pheochromocytoma results from the tumor's secretion of what?

• A. Catecholamines
• B. Insulin
• C. Aldosterone
• D. Growth hormone

Answer: (A)

Hypertension in pheochromocytoma comes from excess catecholamines produced by the tumor. These hormones, mainly epinephrine and norepinephrine, stimulate alpha-adrenergic receptors to cause vasoconstriction, increasing systemic vascular resistance, and stimulate beta-adrenergic receptors to raise heart rate and contractility. The result is high blood pressure, often with spells of headaches, sweating, and palpitations. The other substances don’t fit this pattern: insulin affects glucose metabolism, aldosterone causes sodium and fluid retention through the renin–angiotensin system, and growth hormone affects growth and metabolism but isn’t the primary driver of the hypertension seen in pheochromocytoma.