Pheochromocytoma

Clinical Manifestations

• Screening should be considered for paroxysmal or severe hypertension

Investigations

• Screening tests include:
  • Twenty-four-hour urinary total metanephrines and catecholamines (sensitivity 90%-95%) or 24-hour urine fractionated metanephrines (sensitivity of approximately 95%), with concomitant measurement of 24-hour urine creatinine to confirm accurate collection
  • Plasma free metanephrines and free normetanephrines, where available, might also be considered (sensitivity up to 99%)
  • Urinary vanillylmandelic acid measurements should not be used for screening
• False positive testing may occur in the following settings:
  • Interfering drugs
  • Incorrect patient preparation and positioning (for plasma metanephrine measures)
  • Mild elevation of screening values (ie, less than twofold the upper limit of normal)
  • Normal values on repeat testing
  • Only 1 abnormal biochemical test in the panel of assays
  • Atypical imaging results for pheochromocytoma
  • A low pretest probability of pheochromocytoma
  • Acute illness/hospitalization
• Borderline or indeterminate tests or possible false positive tests can be confirmed by repeating the testing or using the clonidine suppression test (rather than procedding to imaging)
• Imaging (eg, CT, MRI, with or without iodine I-131 meta-iodobenzylguanidine scintigraphy) should generally be performed only after biochemical confirmation of disease

Treatment

• Surgical resection is the definitive treatment
• Requires preoperative planning to control blood pressure
  • a-Blockade should be started 10-14 days preoperatively. Typical options include phenoxybenzamine (a long-acting, nonselective irreversible a-blocker), prazosin, or doxazosin
  • Other antihypertensive medications may be added as necessary but diuretics should be avoided if possible. Oral b-blockers may be considered after achieving adequate a-blockade to control tachycardia and prevent arrhythmias during surgery
  • Volume replacement and liberal sodium intake should be encouraged because volume contraction is common in this condition. Intravenous volume expansion in the perioperative period is recommended to prevent postoperative shock

• Postoperatively, long-term follow-up is recommended with urinary or plasma metanephrine levels to screen for recurrence, especially in those with a genetic predisposition

• Genetic testing should be considered for individuals younger than 50 years of age and for all patients with multiple lesions, malignant lesions, bilateral pheochromocytomas, or paragangliomas, or a family history of pheochromocytoma or paraganglioma