Normetanephrine, Urine Unit Converter

Urine normetanephrine is a metabolite (breakdown product) of norepinephrine, one of the body's main catecholamine hormones involved in the stress response. The enzyme catechol-O-methyltransferase (COMT) converts norepinephrine into normetanephrine, which is then excreted in the urine.

This test measures the amount of normetanephrine excreted in urine over a 24-hour period. Because normetanephrine is produced continuously from norepinephrine metabolism within chromaffin cells, it provides a more stable marker than directly measuring norepinephrine, which fluctuates rapidly.

The test is primarily used to help diagnose or rule out rare catecholamine-producing tumors, including pheochromocytoma (a tumor of the adrenal gland) and paraganglioma (a tumor outside the adrenal glands).

Normetanephrine is produced when norepinephrine is metabolized by catechol-O-methyltransferase (COMT). Approximately 24-40% of circulating normetanephrine originates from the adrenal medulla, with the remainder coming from sympathetic nerve endings throughout the body. The metabolite is eventually excreted by the kidneys into the urine.