Metanephrines free, or metabolites, are breakdown products (metabolites) of the catecholamines epinephrine (adrenaline) and norepinephrine. The plasma free Metanephrines test determines how much Metanephrines and normetanephrine are present in the blood.

Pheochromocytoma, a rare tumour of the adrenal gland, and paraganglioma, a rare tumour outside the adrenal glands, are used to assist identify or rule out these tumours (PPGL); these tumours create excessive amounts of catecholamines, which are then converted to metanephrines.

The breakdown products of the catecholamines epinephrine (adrenaline) and norepinephrine are the two metanephrines, metanephrine and normetanephrine. (metabolites). The plasma free metanephrines test measures the blood's levels of both metanephrine and normetanephrine.

Catecholamines are produced by the sympathetic nervous system, the hormone-producing adrenal glands, and the tiny triangle organs per kidney. (called neurotransmitter substances or neurotransmitters).

Other Names
Plasma Metanephrines The three primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine. Catecholamines are released in response to physical or emotional stress.

They aid in the transmission of nerve impulses in the brain, boost the release of glucose and fatty acids for energy, widen the pupils, and expand the bronchioles—tiny air channels in the lungs. Epinephrine speeds up heart rate and the rate at which the body burns through energy, but norepinephrine also tightens blood vessels, raising blood pressure. (metabolism).

Catecholamines are converted into inactive substances when they have finished their functions.

The breakdown products of epinephrine and norepinephrine are normetanephrine and vanillylmandelic acid (VMA), respectively. The body excretes the hormones and their metabolites in the urine.

Normal levels of catecholamines and their breakdown products can be seen in the blood and urine, but they only significantly rise during and right after a stressful experience.

Why it is done?
To aid in the diagnosis or exclusion of a rare adrenal gland tumour known as a pheochromocytoma or a rare tumour occurring outside the adrenal glands known as a paraganglioma; these tumours (PPGL) produce excess hormones known as catecholamines, which are broken down to Metanephrines.

When Will I Be Tested?
When you (especially if you are younger than 40) experience sudden bursts (paroxysms) of signs and symptoms like high blood pressure (especially if it doesn't respond to standard treatment), severe headaches, rapid heartbeat (palpitations), sweating, tremors, and flushing; when you have a hereditary (genetic) risk for developing PPGL; when your healthcare provider either suspects that you have a tumour that produces catecholamines or wants