What is the initial treatment for pheochromocytoma?

Initial Treatment for Pheochromocytoma

The initial treatment for pheochromocytoma requires alpha-adrenergic blockade for 10-14 days before surgery, with phenoxybenzamine or selective alpha-1 blockers (doxazosin, prazosin, terazosin) as first-line agents to control hypertension and prevent perioperative cardiovascular complications. 1, 2

Preoperative Medical Management

Alpha-Adrenergic Blockade

• Alpha-adrenergic blockade must be initiated at least 7-14 days before surgery with gradually increasing dosages to achieve adequate blood pressure control 1
• Blood pressure targets should be <130/80 mmHg when supine and >90 mmHg systolic when standing 1
• Phenoxybenzamine is FDA-approved specifically for pheochromocytoma to control episodes of hypertension and sweating 3
• Selective alpha-1 blockers (doxazosin, prazosin, terazosin) are effective alternatives and may cause less postoperative hypotension than phenoxybenzamine 1, 4

Beta-Blockers

• Beta-blockers should ONLY be added after adequate alpha blockade to control tachycardia and arrhythmias 1, 5
• Adding beta-blockers before alpha blockade can worsen hypertension due to unopposed alpha-adrenergic stimulation 1
• If tachycardia is excessive despite alpha blockade, beta-blockers are necessary as concomitant therapy 3

Additional Medications

• Calcium channel blockers can be used as adjuncts to alpha-blockers for refractory hypertension or as monotherapy in cases with mild hypertension 1
• Metyrosine (tyrosine hydroxylase inhibitor) may be considered to reduce catecholamine synthesis, but may not be optimal as monotherapy for actively secreting tumors 6, 7

Volume Expansion

• High-sodium diet and administration of 1-2 liters of saline 24 hours prior to surgery should be employed to reduce the risk of orthostatic and postoperative hypotension 1
• Compressive stockings can help manage orthostatic hypotension 1

Comparative Effectiveness of Alpha-Blockers

• Phenoxybenzamine may provide slightly better control of systolic blood pressure but causes more pronounced postoperative hypotension 4
• Doxazosin is associated with fewer side effects such as orthostatic hypotension, edema, and nasal congestion compared to phenoxybenzamine 4
• No significant differences have been observed in operative and postoperative blood pressure control and plasma volume management between phenoxybenzamine, prazosin, and doxazosin 8

Intraoperative Management

• Hypertension during surgery may require treatment with magnesium sulfate, intravenous alpha-adrenoreceptor antagonist (phentolamine), calcium antagonists, nitroprusside, or nitroglycerin 1
• Tachycardia can be treated with intravenous beta-adrenergic receptor blocker (esmolol) 1
• Postoperative hypotension should be prevented by adequate preoperative saline infusion 1

Common Pitfalls and Caveats

• Never initiate beta-blockers before alpha-blockade, as this can precipitate a hypertensive crisis due to unopposed alpha-adrenergic stimulation 1
• Biopsy of suspected pheochromocytoma lesions is contraindicated due to risk of triggering a hypertensive crisis 9
• Metyrosine monotherapy may be insufficient for preoperative management in patients with actively secreting tumors 7
• Monitoring for postoperative hypoglycemia is essential after tumor removal due to sudden decrease in catecholamine levels 1

Post-Treatment Follow-up

• Biochemical testing should be performed 2-8 weeks after surgery to confirm complete resection 1, 10
• Imaging should be done at 3-6 months postoperatively to verify complete tumor removal 1
• Long-term follow-up is necessary as recurrence can occur even decades after initial resection 10