What is the recommended diagnostic workup and pre‑operative management for pheochromocytoma?

Pheochromocytoma: Diagnostic Workup and Pre-operative Management

All patients with suspected pheochromocytoma must undergo biochemical confirmation with plasma free metanephrines (sensitivity 96-100%, specificity 89-98%) before any imaging or intervention, followed by 10-14 days of alpha-adrenergic blockade prior to surgical resection. 1, 2

Diagnostic Workup

Biochemical Testing (First-Line)

Plasma free metanephrines are the single best screening test and should be measured first in all suspected cases. 1, 3, 2 For optimal accuracy, collect blood from an indwelling venous catheter after the patient has been supine for 30 minutes to minimize false positives. 3

• If plasma metanephrines are >4 times the upper limit of normal: Proceed directly to imaging—this confirms pheochromocytoma. 1, 3
• If plasma metanephrines are 1-4 times the upper limit: Perform 24-hour urine collection for fractionated metanephrines and catecholamines to clarify the diagnosis. 3, 2, 4
• If results remain equivocal with strong clinical suspicion: Consider clonidine suppression testing (100% specificity, 96% sensitivity). 3, 4

Common pitfall: Tricyclic antidepressants, obstructive sleep apnea, and obesity can cause false-positive elevations, but these are typically <4 times the upper limit. 3 Most antihypertensive medications do not interfere with LC-MS/MS analysis. 3

Imaging Studies

MRI is the preferred first-line imaging modality because IV contrast used in CT can precipitate a hypertensive crisis. 5, 3 Only use CT after biochemical testing has definitively excluded pheochromocytoma. 5

• Obtain cross-sectional imaging of chest, abdomen, and pelvis to assess for bilateral disease, extra-adrenal paragangliomas, and metastases. 5, 1, 3
• For high-risk features (tumor ≥5 cm, extra-adrenal location, SDHB mutation, or plasma methoxytyramine >3-fold elevated): Add functional imaging with ¹²³I-MIBG scintigraphy or ¹⁸F-FDG PET. 5, 3
• ¹⁸F-FDG PET is superior to MIBG for detecting malignant pheochromocytoma, especially in SDHB mutation carriers. 5, 3

Critical safety point: Fine-needle biopsy of suspected pheochromocytoma is absolutely contraindicated—it can trigger fatal hypertensive crisis. 5, 3

Genetic Testing

Consider genetic testing in all patients, as approximately 30-40% of pheochromocytomas are hereditary. 5, 3, 2, 6 Testing is particularly important for:

• Patients with extra-adrenal paragangliomas (test for SDHx mutations first) 5, 2
• Bilateral adrenal tumors 3
• Age <40 years at diagnosis 5
• Family history of pheochromocytoma or associated syndromes (MEN2, VHL, NF1) 3, 2

SDHB mutations carry 31-71% risk of malignancy and mandate lifelong intensive surveillance. 5, 3

Pre-operative Management

Alpha-Adrenergic Blockade (Mandatory)

Initiate alpha-blockade 10-14 days before surgery in all patients with biochemically confirmed pheochromocytoma. 5, 1, 2

Blood pressure targets:

• <130/80 mmHg supine AND systolic >90 mmHg standing 5

Medication options:

• Phenoxybenzamine (non-selective α-blocker): Start 10 mg twice daily, adjust every 2-4 days. 5
• Doxazosin (selective α1-blocker): May be equally effective with fewer side effects. 5, 7 A 2014 study showed doxazosin provided smoother intraoperative blood pressure control compared to phenoxybenzamine. 7

If target blood pressure is not achieved: Add calcium channel blockers (nifedipine slow-release) or metyrosine. 5

Beta-Blockade (Only After Alpha-Blockade)

Never start beta-blockers before alpha-blockade—this causes unopposed alpha-stimulation and severe hypertensive crisis. 5, 3, 8

• Add beta-blockers only for tachyarrhythmias after adequate alpha-blockade is established. 5
• Use short-acting agents like esmolol intraoperatively for tachycardia. 5

Additional Pre-operative Measures

• High-sodium diet and aggressive fluid intake to prevent postoperative hypotension. 5, 2
• Saline infusion the day before surgery to expand intravascular volume. 5
• For patients with glucocorticoid excess: Administer hydrocortisone 150 mg/day during and after surgery to prevent adrenal crisis. 5

Surgical Approach

Laparoscopic adrenalectomy is the preferred approach for most pheochromocytomas, with open surgery reserved for large (>7 cm) or invasive tumors. 5, 1, 8, 9 A 2026 meta-analysis showed retroperitoneal laparoscopic adrenalectomy had shorter operative time, less blood loss, and fewer complications compared to transabdominal approach. 9

Complete R0 resection is the only curative treatment. 5, 1, 8

Intraoperative Management

• For hypertensive crises: Use magnesium sulfate, phentolamine (IV α-blocker), calcium antagonists, nitroprusside, or nitroglycerin. 5, 1
• For tachycardia: Use IV esmolol (β-blocker). 5, 1
• Anticipate and aggressively treat postoperative hypotension with fluid resuscitation. 5, 1

Postoperative Care

• Monitor glucose levels closely—hypoglycemia commonly occurs after catecholamine levels drop. 5, 1
• Measure plasma or urine metanephrines at 2-8 weeks post-surgery to confirm complete tumor removal. 1, 3

Long-term Surveillance

All patients require lifelong surveillance due to 10-17% recurrence risk and potential for malignancy. 5, 1, 3, 8, 2

Surveillance protocol:

• Clinical monitoring (blood pressure, symptoms): Every 3-4 months for first 2-3 years, then every 6 months. 1, 3
• Biochemical testing (plasma/urine metanephrines, chromogranin A): Every 3-4 months for 2-3 years, then every 6 months. 1, 3
• More intensive surveillance for high-risk patients: SDHB mutations, tumors >5 cm, extra-adrenal location, or PASS score ≥4. 5, 3

Key pitfall: Approximately 17% of patients develop recurrent or new tumors after initial resection, with 9% being malignant. 5 Malignancy can only be confirmed by presence of metastases at sites where chromaffin cells are normally absent. 5