What is Epinephrine (Adrenaline), Urine?
Epinephrine is synthesised exclusively in the adrenal medulla from norepinephrine by phenylethanolamine-N-methyltransferase (PNMT), a reaction that requires high local cortisol concentrations from the adjacent adrenal cortex for PNMT induction — establishing a direct biochemical link between glucocorticoid output and adrenomedullary catecholamine production. Urinary epinephrine therefore specifically reflects adrenomedullary secretory activity, mechanistically distinct from the sympathetic neuronal source of urinary norepinephrine.