What is the degradation product of epinephrine and norepinephrine?

Epinephrine and norepinephrine are catecholamines that primarily undergo metabolic degradation through two key pathways, leading to the production of various metabolites. One of the primary degradation products of these catecholamines is vanillylmandelic acid (VMA).

During the metabolism of epinephrine and norepinephrine, these substances are first converted into homovanillic acid (HVA) and then further metabolized to VMA through a series of enzymatic reactions involving catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). VMA is then ultimately excreted in the urine.

In the context of clinical scenarios, measuring VMA levels can aid in diagnosing conditions that result in excessive catecholamine production, such as pheochromocytoma, a tumor that secretes epinephrine and norepinephrine.

The other metabolites also mentioned, such as HVA and DOPAC, are associated with different pathways. HVA is a primary metabolite of dopamine, and 5-HIAA is a serotonin metabolite. Therefore, VMA is specifically the relevant degradation product for both epinephrine and norepinephrine, confirming it as the correct answer.