Diagnosis:

Physicians may not suspect a pheochromocytoma, because almost half of the people have no symptoms other than persistently high blood pressure. However, when high blood pressure occurs in a young person, comes and goes, or accompanies other symptoms of pheochromocytoma, doctors may request certain laboratory tests. For example, the level of certain catecholamines or products created when these catecholamines are broken down may be measured in blood or urine samples. Because of high blood pressure and other symptoms, doctors may prescribe a beta-blocker before the diagnosis of pheochromocytoma is confirmed.  Beta-blockers can worsen high blood pressure in people with pheochromocytoma. This paradoxical reaction often makes the diagnosis of pheochromocytoma clear.

If the level of catecholamines is high, a computed tomography (CT) or magnetic resonance imaging (MRI) scan can help locate the pheochromocytoma.  A test using injected radioactive chemicals that tend to accumulate in pheochromocytomas is also useful.  A scan is then performed to see where the radioactive chemicals have localized.