What is pheochromocytoma (Pheochromocytoma)?

From the Guidelines

Pheochromocytoma should be managed with surgical removal of the tumor after proper preoperative preparation, which typically includes alpha-blockade with doxazosin or terazosin, followed by a beta-blocker if needed for tachycardia, as recommended by the most recent guidelines 1.

Diagnosis and Treatment

Pheochromocytoma is a rare tumor that develops in the adrenal glands, causing excessive production of catecholamines (adrenaline and noradrenaline). Diagnosis requires biochemical testing with plasma or 24-hour urine metanephrines, followed by imaging studies like CT, MRI, or MIBG scans to locate the tumor.

• The best screening test for pheochromocytoma is plasma free metanephrines (normetanephrine and metanephrine), which carries a high sensitivity and specificity 1.
• Treatment primarily involves surgical removal of the tumor after proper preoperative preparation, which is crucial to prevent hypertensive crisis and other complications.

Preoperative Preparation

This preparation typically includes:

• Alpha-blockade with doxazosin or terazosin, to control blood pressure and prevent adrenergic crises 1.
• Beta-blockade may be added if needed for tachycardia, but alpha-blockade must always precede beta-blockade to prevent hypertensive crisis.

Surgery and Follow-up

Surgery should be performed by experienced surgeons, as these tumors can cause dangerous blood pressure fluctuations during manipulation.

• After surgery, patients require lifelong follow-up to monitor for recurrence or metastatic disease, especially in cases of familial syndromes like MEN2, von Hippel-Lindau disease, or neurofibromatosis.

Special Considerations

In pregnant women, pheochromocytoma is extremely dangerous if undiagnosed, with high maternal and fetal mortality rates 1.

• Early detection and proper treatment during pregnancy can decrease maternal and fetal mortality, and laparoscopic adrenalectomy after medical pre-treatment with alpha-adrenergic blockade is recommended if the tumor is diagnosed within the first 24 weeks of gestation.

From the Research

Medical Management of Pheochromocytoma

• Medical management of pheochromocytoma involves the use of various therapeutic agents, including alpha-adrenergic blocking agents, beta-adrenergic receptor blockers, and catecholamine synthesis inhibitors 2.
• Phenoxybenzamine HCl (Dibenzyline) is an alpha-adrenergic blocking agent that can control the disease in most patients at a dose of 40 to 80 mg per day 2.
• Beta-adrenergic receptor blockade with propranolol is indicated only after adequate alpha-adrenergic blockade in patients with tachycardia and catecholamine-induced arrhythmias 2.

Preoperative Treatment

• Preoperative treatment with an alpha-blocker, such as phenoxybenzamine or doxazosin, is used to prevent hemodynamic instability during surgery 3.
• The combination of alpha-metyrosine and alpha-blockade results in better blood pressure control and less need for antihypertensive medication or pressors during surgery, compared to single-agent adrenergic blockade 4.
• Phenoxybenzamine may be slightly better at controlling systolic arterial pressure, but it can also cause more pronounced postoperative hypotension and side effects such as orthostatic hypotension, edema, and complaints of a stuffy nose 3.

Surgical Management

• Surgical treatment of pheochromocytoma involves the removal of the tumor, and preoperative alpha-blockade therapy is often used to prepare patients for surgery 5.
• The use of a combination of anesthetic agents, such as nitrous oxide, thiopental, narcotics, and enflurane, can ensure smooth induction of anesthesia in most cases 2.
• Careful and prompt control of hypertensive crises with sodium nitroprusside and of arrhythmias with propranolol and lidocaine are critical to the success of surgery 2.

Antihypertensive Management

• Appropriate antihypertensive drugs are used to manage hypertension, control associated cardiovascular symptoms, and prepare patients for operation 6.
• Understanding the pathophysiologic mechanisms that sustain the hypertension and the pharmacology of antihypertensive agents allows for better selection of antihypertensive therapy 6.