This test is used to detect pheochromocytoma, a tumor of the adrenal medulla that secretes excess cathecholamines,
epinephrine and norepinephrine,
Catecholamines are a group of similar hormones produced in the adrenal medulla, the interior portion of the adrenal glands. Adrenal glands are small, triangular organs located on top of each kidney. The primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine.