A pheochromocytoma is a rare tumor that grows in the adrenal glands, the small hormone-producing organs that sit on top of your kidneys. These tumors produce excessive amounts of adrenaline and related stress hormones, causing episodes of dangerously high blood pressure, rapid heartbeat, and intense sweating. With an estimated incidence of about 0.66 cases per 100,000 people per year, most people will never encounter one, but for those who have one, getting it diagnosed and treated is critical.
Where the Tumor Grows and What It Does
Your adrenal glands have two distinct layers. The outer layer produces cortisol and other steroid hormones. The inner layer, called the medulla, contains specialized cells called chromaffin cells that produce adrenaline (epinephrine) and noradrenaline (norepinephrine), the hormones responsible for your fight-or-flight response. A pheochromocytoma develops from these chromaffin cells.
In a healthy adrenal gland, roughly 85% of the output from the medulla is adrenaline. Pheochromocytomas flip that ratio: most of these tumors predominantly secrete noradrenaline instead. Some also produce dopamine, another chemical messenger. The result is a near-constant or episodic flood of stress hormones into your bloodstream, far beyond what your body needs. This is what drives the dramatic symptoms these tumors are known for.
In some cases, these tumors develop outside the adrenal glands entirely, growing along nerve tissue in the abdomen, chest, or pelvis. When they occur in these locations, they’re called paragangliomas rather than pheochromocytomas, though the two are closely related and cause similar problems.
Symptoms and What an Episode Feels Like
The hallmark of a pheochromocytoma is episodic attacks, sometimes called “spells” or “paroxysms.” During an episode, stress hormones surge into your bloodstream and produce a classic triad of symptoms: a sudden pounding headache, profuse sweating, and a racing heart. These episodes can last anywhere from a few minutes to an hour and often come on without warning.
Blood pressure during a spell can spike to dangerous levels, sometimes exceeding 200/100 mmHg. Between episodes, blood pressure may be normal or persistently elevated. Many people also experience anxiety, a feeling of impending doom, trembling, nausea, and pale skin. The intensity varies widely. Some people have multiple attacks per week; others go months between them. Physical exertion, certain body positions, abdominal pressure, and even emotional stress can trigger an episode.
Because these symptoms overlap with panic attacks, anxiety disorders, and more common causes of high blood pressure, pheochromocytomas are frequently misdiagnosed or discovered late. The average time from symptom onset to diagnosis can stretch years.
What Triggers a Dangerous Crisis
Certain medications and foods can provoke a life-threatening surge in blood pressure if you have an undiagnosed pheochromocytoma. Drugs that block specific dopamine receptors, such as the anti-nausea medication metoclopramide, are particularly risky. Metoclopramide can directly stimulate the tumor to release a flood of stress hormones. Beta-blockers given alone (without first blocking the effects of adrenaline through other means) can also worsen a crisis by allowing blood pressure to spike unopposed.
Other problematic medications include monoamine oxidase inhibitors (a class of antidepressants), decongestants containing pseudoephedrine or similar compounds, certain steroid hormones, and some opioid painkillers that trigger histamine release, which in turn provokes the tumor. Foods high in tyramine, a compound found in aged cheeses, cured meats, fermented foods, and some wines, can also increase the availability of stress hormones and trigger or worsen a crisis.
How It’s Diagnosed
Diagnosis relies on measuring the breakdown products of adrenaline and noradrenaline in your blood or urine. These breakdown products, called metanephrines, linger in the bloodstream longer than the hormones themselves, making them easier to detect. There are two main approaches: a blood draw measuring plasma free metanephrines, or a 24-hour urine collection measuring fractionated metanephrines.
Both tests perform well, with urinary metanephrines showing a sensitivity around 92% and plasma metanephrines around 82% in one large study. When both were performed in the same patients, they detected the same number of tumors, but the blood test had a higher specificity (93.5% vs. 88.8%), meaning fewer false alarms. In practice, doctors often start with one and confirm with the other if results are borderline.
Once blood or urine tests confirm excess hormone production, imaging is used to locate the tumor. MRI detects 100% of primary adrenal pheochromocytomas in comparative studies and is often preferred because it doesn’t involve radiation. Standard CT scans detected about 67% in one head-to-head comparison. For tumors that are small, extra-adrenal, or potentially spread to other locations, specialized PET scans using tracers designed to home in on these specific tumor cells offer superior detection. One tracer that targets the amino acid transport system found in these tumors achieved a 100% positivity rate with the highest image clarity scores in prospective testing.
The Genetic Connection
Pheochromocytomas were once thought to be inherited only about 10% of the time, part of a now-outdated “rule of 10s” that guided thinking about these tumors for decades. Current evidence paints a different picture: roughly 25% of patients with apparently sporadic pheochromocytomas carry an identifiable genetic mutation. This means genetic testing is now recommended for nearly everyone diagnosed with one.
Several inherited syndromes are associated with these tumors. Von Hippel-Lindau syndrome, multiple endocrine neoplasia (which affects multiple hormone-producing glands), and Carney-Stratakis syndrome all carry elevated risk. A separate group of mutations in genes that control energy production within cells (the SDH gene family) cause a condition called hereditary paraganglioma-pheochromocytoma, which is classified into four types depending on the specific gene affected. Knowing which mutation you carry matters because it influences where tumors are likely to develop, what hormones they produce, and whether they’re more likely to become malignant.
Treatment and What to Expect Before Surgery
Surgery to remove the tumor is the definitive treatment. But operating on a pheochromocytoma without preparation is dangerous because manipulating the tumor during surgery can trigger massive hormone release. The preparation process is just as important as the operation itself.
For at least seven days before surgery, you’ll take medications that block the effects of adrenaline on your blood vessels, gradually bringing your blood pressure under control. During this period, you’ll also be encouraged to increase your salt and fluid intake, because the chronic high blood pressure from the tumor causes your blood volume to shrink. If your heart rate remains too fast after a week of treatment, a second type of medication to slow the heart is added, typically two to three days before the operation. The sequence matters: slowing the heart before first controlling blood pressure can be dangerous.
The surgery itself is usually performed laparoscopically, through small incisions, for tumors confined to one adrenal gland. Most people recover within a few weeks. Blood pressure often normalizes within days of the tumor being removed, though some people need ongoing blood pressure medication afterward, particularly if they had longstanding hypertension before diagnosis.
Malignancy and Long-Term Outlook
Most pheochromocytomas are benign. The old rule of 10s suggested that 10% were malignant, but updated data shows this figure varies by genetic background. Tumors associated with certain SDH gene mutations, particularly SDHB, carry a notably higher risk of malignancy. A pheochromocytoma is classified as malignant only when it has spread to locations where chromaffin cells are not normally found, such as the liver, lungs, bones, or lymph nodes. There is no reliable way to determine malignancy from the tumor’s appearance under a microscope alone.
Because recurrence and late metastasis can occur years after initial surgery, long-term follow-up with periodic blood or urine testing is standard practice. Annual biochemical screening is typically continued for at least 10 years, and lifelong monitoring is recommended for patients with known genetic mutations. Most people with benign tumors that are completely removed do very well, with blood pressure and quality of life returning to normal.