Urine Metanephrines Test

This biochemical test measures the level of total metanephrines or free metanephrines in a 24-hour urine collection. Metanephrines (metanephrine MN and normetanephrine NMN) are the inactive metabolites of the catecholamine hormones (adrenaline and noradrenaline) that are filtered and excreted by the kidneys. Measuring them in a 24-hour urine sample is an accurate and common diagnostic test for pheochromocytoma and other chromaffin cell tumors, as it reflects the cumulative secretion of the tumor over a full day.