Normetanephrine

Metabolite of norepinephrine

Pathway of noradrenaline breakdown, showing the formation of normetanephrine.

Normetanephrine is a metabolite of the catecholamine norepinephrine, also known as noradrenaline. It is produced through the action of the enzyme catechol-O-methyltransferase (COMT), which methylates norepinephrine. Normetanephrine is an important biomarker in the diagnosis of certain medical conditions, particularly pheochromocytoma and other neuroendocrine tumors.

Biochemistry

Normetanephrine is formed when norepinephrine undergoes methylation by the enzyme catechol-O-methyltransferase. This reaction occurs primarily in the liver and kidneys. The methylation of norepinephrine results in the addition of a methyl group to the catecholamine, converting it into normetanephrine.

File:Normetanephrine.svg

Chemical structure of normetanephrine.

Once formed, normetanephrine can be further metabolized into vanillylmandelic acid (VMA), which is excreted in the urine. The levels of normetanephrine and its metabolites in the body can be measured to assess catecholamine metabolism and to aid in the diagnosis of certain diseases.

Clinical Significance

Normetanephrine is clinically significant as a biomarker for the diagnosis of pheochromocytoma, a type of tumor that arises from the adrenal medulla and secretes excessive amounts of catecholamines. Elevated levels of normetanephrine in the blood or urine can indicate the presence of such tumors.

In addition to pheochromocytoma, elevated normetanephrine levels may also be observed in other conditions associated with increased catecholamine production, such as neuroblastoma and certain forms of hypertension.

Measurement

The measurement of normetanephrine levels is typically performed using high-performance liquid chromatography (HPLC) or mass spectrometry. These methods allow for the precise quantification of normetanephrine and its related metabolites in biological samples such as blood plasma and urine.

Related Pages

• Norepinephrine
• Catecholamine
• Pheochromocytoma
• Vanillylmandelic acid
• Catechol-O-methyltransferase