Normetanephrine

Normetanephrine is a metabolite of the hormone norepinephrine, which is produced by the adrenal glands. It is primarily used as a biomarker in the diagnosis of pheochromocytoma, a rare tumor of the adrenal glands.

Production and Function

Normetanephrine is produced when norepinephrine is metabolized by the enzyme catechol-O-methyl transferase (COMT). This process occurs mainly in the neurons and adrenal glands. The primary function of normetanephrine is to serve as a marker for the presence of certain diseases, most notably pheochromocytoma.

Clinical Significance

Elevated levels of normetanephrine in the blood or urine can indicate the presence of a pheochromocytoma. This is because these tumors produce excessive amounts of norepinephrine, which is then metabolized into normetanephrine. Therefore, testing for normetanephrine is a key part of the diagnostic process for this condition.

In addition to pheochromocytoma, elevated normetanephrine levels can also be seen in other conditions such as paraganglioma, neuroblastoma, and certain types of stress or anxiety disorders.

Measurement

Normetanephrine levels can be measured in both blood and urine. The most common method of measurement is through a 24-hour urine collection, which provides a more accurate reflection of the body's production of this metabolite. Blood tests can also be used, but they are generally less accurate and more susceptible to fluctuations in normetanephrine levels throughout the day.

See Also

• Norepinephrine
• Pheochromocytoma
• Catechol-O-methyl transferase
• Adrenal glands