Normetanephrine is one of the breakdown products, or metabolites, of norepinephrine, which is a neurotransmitter and hormone present in the body. It is primarily responsible for increasing the heart rate and blood pumping from the heart. Thereby, playing a defining role in the body’s “fight or flight” response. Norepinephrine is one of the catecholamine compounds, a group of substances released into the blood during physical or emotional stress. Usually, these are produced by the adrenal glands or by the cells of the nervous system. The various functions of catecholamines are as follows:

• Transmitting nerve impulses in the brain
• Dilating the bronchioles (small air passages present in the lung)
• Dilating the pupils
• Constricting blood vessels to increase blood pressure
• Increasing the heart rate
• Boosting the rate at which the body uses energy

Since catecholamine compounds only fulfil a specific purpose, they are broken down into inactive compounds. In the case of norepinephrine, it is turned into normetanephrine and vanillylmandelic acid (VMA), which are then expelled in the form of urine. However, certain tumours in the adrenal gland (pheochromocytoma) and outside the adrenal gland (paraganglioma) may cause large amounts of catecholamine compounds to be released, along with their metabolites. Due to this, large concentrations of these elements can be found in the blood.
The normetanephrines-free test is used to detect the presence of these compounds in the blood. Hence, it helps in the determination of tumours. Since the usual normetanephrine levels in the plasma are low, a high count indicates the likelihood of an adrenal tumour. Due to the composition of normetanephrine in both the blood and urine, this test may require both of these samples. The procedure for the normetanephrines-free blood test is standard, with the clinical lab technician drawing blood from the vein in the arm. The sample is then stored carefully in a labelled container and sent for analysis. The doctor usually recommends a blood test during specific symptoms. These are:

• Persistent hypertension
• A sudden burst of hypertension (paroxysm)

On the other hand, the normetanephrines-free urine test requires a 24-hour urine sample for analysis. Usually, the lab provides a labelled container, which has to be filled with urine in a 24-hour period.
Usually, the lab technician will ask that the sample be refrigerated and provide a preservative along with it so that the results are accurate.

Some of the symptoms that may require seeking medical attention for adrenal gland tumours are:

• Severe headaches
• Rapid heart rate (especially without engaging in any physical activity or stress)
• Tremor
• Constant sweating
• Flushing

A doctor might better help understand these symptoms and, if necessary, recommend a normetanephrines-free urine test to gauge the reason.