Merck Manual

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Ashley B. Grossman

, MD, University of Oxford; Fellow, Green-Templeton College

Reviewed/Revised Feb 2024

A pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells typically located in the adrenals. It causes persistent or paroxysmal hypertension. Diagnosis is by measuring catecholamine products in blood or urine. Imaging tests, especially CT or MRI, help localize tumors. Treatment involves removal of the tumor when possible. Alpha-blockade, usually combined with beta-blockade, is used to control blood pressure.

The catecholamines secreted include norepinephrine, epinephrine, dopamine, and dopa in varying proportions.

Most pheochromocytomas are in the

Pheochromocytomas may also be located in other tissues derived from neural crest cells. Possible sites include the following:

  • Paraganglia of the sympathetic chain

  • Retroperitoneally along the course of the aorta

  • Carotid body

  • Organ of Zuckerkandl (at the aortic bifurcation)

  • Genitourinary system

  • Brain

  • Pericardial sac

  • Dermoid cysts

Pheochromocytomas in the adrenal medulla occur equally in both sexes, are bilateral in 10% of cases (20% in children), and are malignant in < 10% (1 General reference A pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells typically located in the adrenals. It causes persistent or paroxysmal hypertension. Diagnosis is by measuring catecholamine... read more ). Of extra-adrenal pheochromocytomas (known as paragangliomas), 30% are malignant. Although pheochromocytomas occur at any age, peak incidence is between 20 and 40 years. Nearly 50% are thought to be due to germline mutations. Extra-adrenal pheochromocytomas are more likely to be malignant and metastasize.

Pheochromocytomas vary in size but average 5 to 6 cm in diameter. They weigh 50 to 200 g, but tumors weighing several kilograms have been reported. Rarely, they are large enough to be palpated or cause symptoms due to pressure or obstruction. Regardless of the histologic appearance, the tumor is considered benign if it has not invaded the capsule and no metastases are found, although exceptions occur. In general, larger tumors are more likely to be recurrent or metastatic.

Pheochromocytomas may be part of the syndrome of familial multiple endocrine neoplasia Overview of Multiple Endocrine Neoplasias (MEN) The multiple endocrine neoplasia (MEN) syndromes comprise 4 genetically distinct familial diseases involving adenomatous hyperplasia and malignant tumors in several endocrine glands. MEN 1 involves... read more (MEN) types 2A and 2B, in which other endocrine tumors (parathyroid carcinoma or medullary carcinoma of the thyroid) coexist or develop subsequently. Pheochromocytoma develops in 1% of patients with neurofibromatosis Neurofibromatosis Neurofibromatosis refers to several related genetic disorders that have overlapping clinical manifestations. It causes various types of benign or malignant tumors that involve central or peripheral... read more Neurofibromatosis and may occur with hemangioblastomas and renal cell carcinoma Renal Cell Carcinoma Renal cell carcinoma (RCC) is the most common renal cancer. Symptoms can include hematuria, flank pain, a palpable mass, and fever of unknown origin (FUO). However, symptoms are often absent... read more Renal Cell Carcinoma , as in von Hippel-Lindau disease Von Hippel–Lindau Disease (VHL) Von Hippel-Lindau disease is a rare hereditary neurocutaneous disorder characterized by benign and malignant tumors in multiple organs. Diagnosis is made using clinical criteria and/or molecular... read more Von Hippel–Lindau Disease (VHL) . Familial pheochromocytomas and carotid body tumors may be due to mutations in genes encoding the enzyme succinate dehydrogenase or other signaling molecules.

Paragangliomas arising in the head or neck originate from chromaffin cells in parasympathetic ganglia, can secrete catecholamines, and are referred to as head-and-neck paragangliomas.

General reference

  • 1. Pacak K, Tella SH. Pheochromocytoma and Paraganglioma. [Updated 2018 Jan 4]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA):, Inc.; 2000-. Available from:

Symptoms and Signs of Pheochromocytoma

  • Tachycardia

  • Diaphoresis

  • Postural hypotension

  • Tachypnea

  • Cold and clammy skin

  • Severe headache

  • Angina

  • Palpitations

  • Nausea and vomiting

  • Epigastric pain

  • Visual disturbances

  • Dyspnea

  • Paresthesias

  • Constipation

  • A sense of impending doom

Paroxysmal attacks may be provoked by palpation of the tumor, postural changes, abdominal compression or massage, induction of anesthesia, emotional trauma, unopposed beta-blockade (which paradoxically increases blood pressure by blocking beta-mediated vasodilation), or micturition (if the tumor is in the bladder). In older patients, severe weight loss with persistent hypertension is suggestive of pheochromocytoma.

Physical examination, except for the presence of hypertension, is usually normal unless done during a paroxysmal attack. Retinopathy and cardiomegaly are often less severe than might be expected for the degree of hypertension, but a specific catecholamine cardiomyopathy can occur. However, cardiac and cerebrovascular events are more frequent in patients with pheochromocytomas than in others with similar blood pressure levels.

Symptoms and signs reference

  • 1. Wang X, Zhao Q, Sang H, Dong J, Bai M. Research on the Damage of Adrenal Pheochromocytoma to Patients' Cardiovascular Vessels and Its Correlation with Hypertension. J Oncol 2022;2022:3644212. Published 2022 Feb 11. doi:10.1155/2022/3644212

Diagnosis of Pheochromocytoma

  • Plasma free metanephrines or urinary metanephrines

  • Chest and abdomen imaging (CT or MRI) if catecholamine screen positive

  • Nuclear imaging with Gallium-68 dotatate-PET scanning

Pheochromocytoma is suspected in patients with typical symptoms or particularly sudden, severe, or intermittent unexplained hypertension, especially in younger patients and those with resistant hypertension. Diagnosis involves demonstrating high levels of catecholamine products in the serum or urine.

Blood tests

Plasma free metanephrines are up to 99% sensitive with either metanephrine or more frequently normetanephrine being elevated. This test has superior sensitivity to measurement of circulating epinephrine and norepinephrine because plasma metanephrines are elevated continuously, unlike epinephrine and norepinephrine, which are secreted intermittently. Grossly elevated plasma norepinephrine renders the diagnosis highly probable. Plasma 3-methoxytyramine is a metabolite of dopamine and is indicative of a more aggressive tumor.

Urine tests

Urinary metanephrine and normetanephrine levels are slightly less specific for pheochromocytoma than plasma free metanephrine, but elevation of either metabolite has approximately 95% sensitivity . Two or 3 normal results while the patient is hypertensive render the diagnosis extremely unlikely. Measurement of urinary norepinephrine and epinephrine is less accurate.

The principal urinary metabolic products of epinephrine, norepinephrine, and dopamine are the

  • Metanephrines (metanephrine and normetanephrine)

  • Vanillylmandelic acid (VMA), which is another metabolite of epinephrine and norepinephrine

  • Homovanillic acid (HVA), which is a metabolite of dopamine

Healthy people excrete only very small amounts of these substances. Normal values for 24 hours are as follows:

  • Free epinephrine and norepinephrine < 100 mcg (< 582 nmol)

  • Total metanephrine < 1.3 mg (< 7.1 micromole), but fractionated metanephrine and normetanephrine are preferable

  • VMA < 10 mg (< 50 micromoles), which is now rarely used

  • HVA < 15 mg (< 82.4 micromoles), which is mainly used to detect neuroblastoma in children

In pheochromocytoma, increased urinary excretion of epinephrine and norepinephrine and their metabolic products is intermittent. Elevated excretion of these compounds may also occur in

Other tests

Blood volume is constricted and may falsely elevate hemoglobin and hematocrit levels. Hyperglycemia, glycosuria, or overt diabetes mellitus Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more may be present, with elevated fasting levels of plasma free fatty acid and glycerol. Plasma insulin level is inappropriately low for the plasma glucose. After removal of the pheochromocytoma, hypoglycemia Hypoglycemia Hypoglycemia, or low plasma glucose level can result in sympathetic nervous system stimulation and central nervous system dysfunction. In patients with diabetes who take insulin or antihyperglycemic... read more may occur, especially in patients treated with oral antihyperglycemics.

Provocative tests with histamine or tyramine are hazardous and should not be used. Glucagon 0.5 to 1 mg injected rapidly IV provokes a rise in blood pressure of > 35/25 mm Hg within 2 minutes in normotensive patients with pheochromocytoma, but its use is now generally unnecessary. Phentolamine must be available to terminate any hypertensive crisis.

Pearls & Pitfalls

  • Provocative tests with histamine or tyramine are hazardous and are unnecessary.

A suppression test using oral clonidine or IV pentolinium can be used in patients with elevated plasma catecholamines but is rarely necessary.

Imaging tests to localize tumors are usually done in patients with abnormal blood and urine test results. Tests should include CT and MRI of the chest and abdomen with and without contrast. With isotonic contrast agents, no adrenoceptor blockade is necessary. Fluorodeoxyglucose (FDG)-PET has also been used successfully, especially in patients with succinate dehydrogenase mutations, but Gallium-68 dotatate-PET scanning is more sensitive.

During catheterization of the vena cava, repeated sampling of plasma catecholamine concentrations at different locations, including the adrenal veins, can help localize the tumor; there will be an increase in norepinephrine level in a vein draining the tumor. Adrenal vein norepinephrine:epinephrine ratios may help in the hunt for a small adrenal source, but determining these ratios is now rarely necessary.

Radiopharmaceuticals with nuclear imaging techniques can also help localize pheochromocytomas. Radionuclide imaging is rapidly advancing, and increasingly metaiodobenzylguanidine (I-123 MIBG) is being replaced by Gallium-68 dotatate-PET scanning.

Signs of an associated genetic disorder (eg, café-au-lait patches in neurofibromatosis) should be sought. Patients should be screened for MEN with a serum calcitonin measurement and any other tests as directed by clinical findings. Most centers routinely do genetic testing, especially when the pheochromocytoma involves the sympathetic paraganglia and in younger patients, but probably all patients with pheochromocytoma should have genetic testing.

Treatment of Pheochromocytoma

  • Hypertension control with combination of alpha-blockers and then beta-blockers

  • Surgical removal of tumor with careful perioperative control of blood pressure and volume status

Surgical removal is the treatment of choice. The operation is usually delayed until hypertension is controlled by a combination of alpha-blockers and beta-blockers (usually phenoxybenzamine 20 to 40 mg orally 3 times a day and propranolol 20 to 40 mg orally 3 times a day).

The blood pressure target is < 130/80 mmHg; some suggest the target should also include achieving a certain postural drop in blood pressure, but this is not essential. Re-equilibration of the cardiovascular system requires approximately 10 to 14 days, after which blockade is presumed to be effective. Beta-blockers should not be used until adequate alpha-blockade has been achieved. Some alpha-blockers, such as doxazosin, may be equally effective but better tolerated.

Nitroprusside can be infused for hypertensive crises preoperatively or intraoperatively.

Pearls & Pitfalls

  • Give alpha-blockers first before beta-blockers. Unopposed beta-2-blockade can cause paradoxical increase in blood pressure by blocking beta-mediated vasodilation.

When bilateral tumors are documented or suspected (as in a patient with multiple endocrine neoplasia Overview of Multiple Endocrine Neoplasias (MEN) The multiple endocrine neoplasia (MEN) syndromes comprise 4 genetically distinct familial diseases involving adenomatous hyperplasia and malignant tumors in several endocrine glands. MEN 1 involves... read more [MEN]), sufficient hydrocortisone (100 mg IV twice a day) given before and during surgery avoids acute glucocorticoid insufficiency due to bilateral adrenalectomy. Sometimes cortical-sparing surgery is an alternative.

Most pheochromocytomas can be removed laparoscopically. Blood pressure must be continuously monitored via an intra-arterial catheter Arterial Catheterization A number of procedures are used to gain vascular access. Most patients’ needs for IV fluid and drugs can be met with a percutaneous peripheral venous catheter. If blind percutaneous placement... read more Arterial Catheterization , and volume status is closely monitored. Anesthesia should be induced with a nonarrhythmogenic drug and continued with an inhaled drug (eg, enflurane, isoflurane). During surgery, paroxysms of hypertension should be controlled with injections of phentolamine 1 to 5 mg IV or nitroprusside infusion (2 to 4 mcg/kg/minute), and tachyarrhythmias should be controlled with propranolol or esmolol. If a muscle relaxant is needed, drugs that do not release histamine are preferred. Atropine should not be used preoperatively.

Preoperative blood transfusion (1 to 2 units) may be given before the tumor is removed in anticipation of blood loss. If blood pressure has been well controlled before surgery, a diet high in salt is recommended to increase blood volume. An infusion of norepinephrine 4 to 12 mg/L in a dextrose-containing solution beginning at 0.05 mcg/kg/minute and titrated to effect may be considered if hypotension develops. Some patients whose hypotension responds poorly to norepinephrine may benefit from hydrocortisone 100 mg IV, but adequate fluid replacement is usually all that is required.

Malignant metastatic pheochromocytoma should be treated with alpha-blockers and beta-blockers. The tumor may be indolent and survival long-lasting. However, even with rapid tumor growth, blood pressure can be controlled. I-131 MIBG or more recently lutetium-177 dotatate can help relieve symptoms in patients with residual disease. Metyrosine, a tyrosine hydroxylase inhibitor, may be used to decrease catecholamine production in patients whose blood pressure is difficult to control. Radiation therapy may reduce bone pain due to metastases. Chemotherapy is rarely effective, but the most common regimen tried is the combination of cyclophosphamide, vincristine, and dacarbazine. The chemotherapy agent temozolomide and targeted therapy with sunitinib or possibly cabozantinib may also be effective. Belzutifan, a hypoxia-inducible factor inhibitor used in the treatment of associated cancers in patients with von Hippel-Lindau disease Von Hippel–Lindau Disease (VHL) Von Hippel-Lindau disease is a rare hereditary neurocutaneous disorder characterized by benign and malignant tumors in multiple organs. Diagnosis is made using clinical criteria and/or molecular... read more Von Hippel–Lindau Disease (VHL) , is currently undergoing clinical trials in patients with malignant metastatic pheochromocytoma.

Key Points

  • Hypertension may be constant or episodic.

  • Diagnosis involves demonstrating high levels of catecholamine products (typically plasma free metanephrines in the serum or 24-hour metanephrines in the urine).

  • Tumors should be localized with imaging tests, usually including using radiolabeled compounds.

  • A combination of alpha-blockers and beta-blockers are given pending tumor removal.

  • Genetic tesing should be done to plan optimal follow-up for the patient and to identify family members at risk.

Drugs Mentioned In This Article

Drug Name Select Trade
BAQSIMI, GlucaGen, Glucagon, Gvoke, Gvoke HypoPen, Gvoke PFS
Catapres, Catapres-TTS, Duraclon, Kapvay, NEXICLON XR
HEMANGEOL, Inderal, Inderal LA, Inderal XL, InnoPran XL
Cardura, Cardura XL
NIPRIDE RTU , Nitropress
A-Hydrocort, Ala-Cort, Ala-Scalp, Alkindi, Anucort-HC, Anumed-HC, Anusol HC, Aquaphor Children's Itch Relief, Aquaphor Itch Relief, Balneol for Her, Caldecort , Cetacort, Colocort , Cortaid, Cortaid Advanced, Cortaid Intensive Therapy, Cortaid Sensitive Skin, CortAlo, Cortef, Cortenema, Corticaine, Corticool, Cortifoam, Cortizone-10, Cortizone-10 Cooling Relief, Cortizone-10 External Itch Relief, Cortizone-10 Intensive Healing, Cortizone-10 Plus, Cortizone-10 Quick Shot, Cortizone-5 , Dermarest Dricort, Dermarest Eczema, Dermarest Itch Relief, Encort, First - Hydrocortisone, Gly-Cort , GRx HiCort, Hemmorex-HC, Hemorrhoidal-HC, Hemril , Hycort, Hydro Skin, Hydrocortisone in Absorbase, Hydrocortone, Hydroskin , Hydroxym, Hytone, Instacort, Lacticare HC, Locoid, Locoid Lipocream, MiCort-HC , Monistat Complete Care Instant Itch Relief Cream, Neosporin Eczema, NuCort , Nutracort, NuZon, Pandel, Penecort, Preparation H Hydrocortisone, Proctocort, Proctocream-HC, Procto-Kit, Procto-Med HC , Procto-Pak, Proctosert HC , Proctosol-HC, Proctozone-HC, Rectacort HC, Rectasol-HC, Rederm, Sarnol-HC, Scalacort, Scalpicin Anti-Itch, Solu-Cortef, Texacort, Tucks HC, Vagisil Anti-Itch, Walgreens Intensive Healing, Westcort
Forane, Terrell
Atreza, Atropine Care , Atropisol , Isopto Atropine, Ocu-Tropine, Sal-Tropine
Advocate Glucose SOS, BD Glucose, Dex4 Glucose, Glutol , Glutose 15 , Glutose 45 , Glutose 5
Cyclophosphamide, Cytoxan, Neosar
Oncovin, Vincasar PFS
Cabometyx , COMETRIQ
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