The Full Form of VMA is‍ Vanillylmandelic acid.

Vanillylmandelic acid (VMA) is one of the breakdown products (metabolites) of epinephrine (adrenaline) and norepinephrine. Epinephrine and norepinephrine belong to a group of similar hormones called catecholamines. This test measures the amount of VMA that is passed into the urine, typically over a 24-hour period, to detect excess epinephrine and norepinephrine. It is used to detect tumors called neuroblastomas and other neuroendocrine tumors.

Catecholamines are produced in the central portion of the adrenal glands, the adrenal medulla. Adrenal glands are small triangular organs located on top of each kidney. The primary catecholamines released are dopamine, epinephrine, and norepinephrine. These hormones are released into the bloodstream in response to physical or emotional stress. They help transmit nerve impulses in the brain, increase glucose and fatty acid release for energy, dilate bronchioles, and dilate the pupils. Norepinephrine also constricts blood vessels, increasing blood pressure, and epinephrine increases heart rate and metabolism.

After completing their actions, the catecholamines are metabolized to inactive compounds. Dopamine becomes homovanillic acid (HVA), norepinephrine breaks down into normetanephrine and VMA, and epinephrine becomes metanephrine and VMA. Both the hormones and their metabolites are eliminated from the body in the urine. VMA is usually present in the urine in small fluctuating amounts that only increase appreciably during and shortly after the body is exposed to a stressor.

Sometimes, tumors begin to form in the cells of the neuroendocrine system, which is made up of a combination of cells that produce hormones and nerve cells. These types of cells are found throughout the body in organs such as the lungs and the digestive system. Tumors that form in these cells are called neuroendocrine tumors.