Metanephrine, Urine Unit Converter

Urine metanephrines are breakdown products (metabolites) of catecholamines, the hormones that control your body's "fight or flight" response. The test measures two main compounds: metanephrine (from epinephrine/adrenaline) and normetanephrine (from norepinephrine/noradrenaline).

The 24-hour urine collection captures the total amount of these metabolites excreted over a full day, providing a more complete picture than a single blood sample. This makes it especially useful for detecting tumors that release catecholamines in episodic bursts.

The test is primarily used to screen for pheochromocytoma (a rare adrenal gland tumor) and paraganglioma (a similar tumor outside the adrenal glands). These tumors produce excess catecholamines that can cause dangerous spikes in blood pressure.

Metanephrines are produced when the enzyme catechol-O-methyltransferase (COMT) breaks down catecholamines. The adrenal medulla (the inner part of the adrenal glands) is the primary source of metanephrine, while normetanephrine comes from both the adrenal medulla and sympathetic nerve endings throughout the body. These metabolites are then filtered by the kidneys and excreted in urine.