Final answer:
The ultimate end product of both epinephrine and norepinephrine metabolism is Vanillylmandelic acid (VMA), formed through the action of liver enzymes such as COMT and MAO, and excreted in urine.
Step-by-step explanation:
The ultimate end product of both epinephrine and norepinephrine metabolism is Vanillylmandelic acid (VMA). In the liver, these catecholamines are metabolized by enzymes such as Catechol-O-Methyl-Transferase (COMT) and Mono-Amine Oxidase (MAO), leading to the formation of O-methylated and deaminated metabolites. Vanillylmandelic acid (VMA) is the major product excreted in the urine and is used to assess catecholamine-producing tumors and other conditions related to catecholamine secretion.