What is the initial treatment for pheochromocytoma?

Initial Treatment for Pheochromocytoma

The initial treatment for pheochromocytoma is alpha-adrenergic blockade for 10-14 days before surgical intervention, with phenoxybenzamine or selective alpha-1 blockers (doxazosin, prazosin, terazosin) as first-line agents. 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 control blood pressure and prevent perioperative hypertensive crises 1
• Target blood pressure goals are <130/80 mmHg when supine and systolic blood pressure >90 mmHg when standing 1
• Two main options for alpha blockade include:
  • Non-selective alpha blocker: Phenoxybenzamine (FDA-approved specifically for pheochromocytoma) 2
  • Selective alpha-1 blockers: Doxazosin, prazosin, or terazosin 1, 3

Medication Selection Considerations

• Phenoxybenzamine may provide better intraoperative hemodynamic stability but causes more postoperative hypotension 3
• Selective alpha-1 blockers (doxazosin, prazosin, terazosin) have fewer side effects but may require additional antihypertensive medications for optimal control 3
• Phenoxybenzamine more commonly causes orthostatic hypotension, edema, and nasal congestion compared to selective alpha-1 blockers 3

Additional Preoperative Measures

• Beta-blockers should ONLY be added after adequate alpha blockade to control tachyarrhythmias, never before alpha blockade (to avoid hypertensive crisis from unopposed alpha stimulation) 1, 4
• Calcium channel blockers can be used as adjuncts to alpha-blockers for refractory hypertension 1
• High-sodium diet and administration of 1-2 liters of saline 24 hours prior to surgery, along with compressive stockings, should be employed to reduce the risk of orthostatic and postoperative hypotension 1

Surgical Management

• Laparoscopic adrenalectomy is the preferred surgical approach for most pheochromocytomas 1
• Open surgery should be considered for tumors with high suspicion of malignancy, large size (>6 cm), or local invasion 1
• Complete surgical extirpation (R0 resection) is the mainstay of potentially curative approaches 1

Intraoperative Management

• Hypertension during surgery may be treated 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

Special Considerations

• For pregnant patients with pheochromocytoma diagnosed within the first 24 weeks of gestation, laparoscopic adrenalectomy after 10-14 days of medical pre-treatment with alpha-adrenergic blockade is recommended 5
• If the tumor is diagnosed in the third trimester, medical management until fetal viability followed by cesarean section with tumor removal in the same session is recommended 5

Common Pitfalls and Caveats

• Never initiate beta-blockers before adequate alpha blockade, as this can precipitate a hypertensive crisis due to unopposed alpha-adrenergic stimulation 1, 4
• Fine needle biopsy of suspected pheochromocytoma is contraindicated due to risk of hypertensive crisis 6
• Patients require careful monitoring for hypoglycemia after surgery due to the sudden reduction in catecholamine levels 1
• Postoperative biochemical testing should be performed 2-8 weeks after surgery to confirm complete resection 1

Despite various options for preoperative alpha blockade, there is no conclusive evidence showing superiority of one agent over another in terms of perioperative outcomes, though phenoxybenzamine remains the only FDA-approved medication specifically indicated for pheochromocytoma 2, 3.