The 24-hour urine catecholamine test is a quantitative analysis that measures the excretion of three key hormones (epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine) and their major metabolites (such as metanephrine) in urine collected over a full day. This measurement reflects the total production of these hormones and is a key diagnostic test for pheochromocytoma and paraganglioma.