appropriate perioperative management of pheochromocytomas
Surgical resection is the only chance for cure for patients with pheochromocytomas. All patients with the biochemical diagnosis of a pheochromocytoma should undergo preoperative alpha-adrenergic blockade for 7 to 14 days to prevent unstable intraoperative blood pressure. Phenoxybenzamine is a nonselective long-acting alpha-adrenergic blocker; the starting dose is 10 mg twice daily and the dosage is titrated up to achieve the goals of treatment. Short-acting alpha-adrenergic blockers (prazosin, doxazosin, terazosin) and calcium channel blockers (nicardipine) are alternative options.
Preoperative beta-adrenergic receptor blockade is indicated for tachyarrhythmias only after alpha-adrenergic blockade is established. Propranolol (10–40 mg every 6 to 8 hours) is the most commonly used beta-blocker in this scenario.
The goals of treatment are a blood pressure < 130/80 mm Hg seated and > 90 systolic when standing; the heart rate should be 60 to 70 beats per minute seated and 70 to 80 beats per minute standing.
Patients should increase their fluid and salt intake (> 5 g/day) after starting alpha-blockers to attain fluid expansion because they have intravascular volume depletion.
Genetic testing is recommended for all patients with pheochromocytoma because it is now known that up to 40% of cases are hereditary. Also, lifelong annual biochemical testing to assess for recurrent or metastatic disease is recommended because up to 25% of pheochromocytomas are malignant, and the malignant nature of pheochromocytomas (metastases) may not be apparent for many years (up to 40 years) after the initial resection. Patients with mutations encoding succinate dehydrogenase subunit B (SDHB) have a 40% chance of metastatic disease.
Chromogranin A is a nonspecific marker of neuroendocrine tumors and is commonly used as a marker for monitoring disease as it is elevated in 91% of patients with pheochromocytomas and should be checked prior to adrenalectomy.