Blood and Urine Tests for Pheochromocytoma

What Blood and Urine Tests are Required for Pheochromocytoma of the Adrenal Gland?

Laboratory testing of the blood or urine is the primary way to determine whether a pheochromocytoma is present. But first, the diagnosis of pheochromocytoma hinges on the treating physician considering the diagnosis in the first place. The tests measure metanephrines (metanephrine and normetanephrine). These are not the adrenaline-type hormones (catecholamines) themselves but their breakdown products. A tumor releases adrenaline in bursts, but it makes metanephrines all the time, which is why metanephrines are the more reliable test; older tests such as plasma catecholamines or urine VMA are no longer used for screening. One of the following two tests is used:

• Measurement of plasma free metanephrines (metanephrine and normetanephrine). This blood test is very sensitive: a normal result makes a pheochromocytoma very unlikely. A level more than about 3 times the upper limit of normal almost always indicates the presence of a pheochromocytoma or paraganglioma.
• 24-hour collection of urine fractionated metanephrines. This urine test is also accurate and can be used instead of the blood test or to confirm it.

How to Prepare, and What a Mildly High Result Means. The blood sample is ideally drawn after you have been lying down and resting for 20–30 minutes. A sample taken sitting up, in a hurry or under stress is more likely to be falsely high. Mild elevations (less than about 3 times the upper limit of normal) are common and are more often caused by medications, stress, illness or the way the blood was drawn than by a tumor. They should be repeated under the right conditions before any conclusion is drawn. Children need age-specific reference ranges.

Drugs and Medications that Can Affect Laboratory Testing for Pheos. Many medications may affect (increase) the test results, so tell us and your doctor what medications (if any) you were taking while being tested. Do not stop a prescribed medication without asking your doctor.

This list shows some of the medications and substances that may interfere with the measurement of metanephrines:
• Tricyclic antidepressants (including cyclobenzaprine)
• Levodopa
• Buspirone and antipsychotic agents
• Serotonin and noradrenaline reuptake inhibitors
• Monoamine oxidase inhibitors
• Drugs containing adrenergic receptor agonists (e.g., decongestants)
• Amphetamines and other stimulants
• Prochlorperazine
• Withdrawal from clonidine or alcohol
• Illicit drugs (e.g., cocaine)

Who should be tested? Anyone with symptoms that suggest a pheochromocytoma, anyone with an adrenal mass found on a scan (an adrenal incidentaloma), and anyone who carries one of the inherited gene changes. See the full list on our pheochromocytoma overview page.

Once it has been established that the metanephrines are elevated, a scan is used to locate the tumor, usually a CT or an MRI. Scans for pheochromocytoma and paraganglioma are discussed on our pheochromocytoma scans page. Genetic testing should be offered to every patient with a pheochromocytoma or paraganglioma, because about 30–40% are hereditary.

IMPORTANT: If you have a pheochromocytoma or paraganglioma, you need to be prepared for surgery. Most patients are treated with blood-pressure medication (alpha-blockers such as doxazosin or phenoxybenzamine, sometimes other medicines) and good hydration, usually for 1-2 weeks before the operation; the plan is individualized by the team.

After surgery: the same metanephrine test is repeated every year for life, because a pheochromocytoma can come back or a new one can form many years later.

Last updated October 2026.