The most effective way to diagnose pheochromocytomas or paragangliomas is through biochemical testing that measures catecholamines and metanephrines in plasma or urine.

Experts suggest that analysis of free metanephrines in blood plasma is the most accurate test for detecting these tumors.

Urine tests, although not quite as sensitive as plasma testing, are still considered effective in diagnosis.

Other diagnostic tests that are sometimes used include CT scan with the use of various chemicals and MRI. These scans should be performed in centers that have a level of comfort in diagnosing this disease and offer at least FDG-PET scanning.  Without the proper scans, a complete picture of the tumor, which are usually multifocal, cannot be made.  It is as a result of these scans that a surgical plan for treatment and the sub-specialist surgeons that will participate are chosen.