What is VMA?
Catecholamines are produced by a part of the adrenal gland, called the medulla (the central part of the gland, as opposed to the cortex, which is the outer area). The 2 main catecholamine hormones are called adrenaline (or epinephrine) and noradrenaline (or norepinephrine). They can be tested in the blood, but most often are measured in the urine, along with their metabolic end products, VMA (vanillylmandelic acid) and HVA (homovanillic acid). The majority (not all!) of neuroblastoma’s produce the catecholamine metabolites, VMA and HVA. So, testing the urine is very often done to detect disease. It’s also used as an indictor for response to treatment. For example, a child newly dx with neuroblastoma with higher than normal levels (remember, these metabolites are normally found in the urine, anyway) of VMA, would be expected to see the levels drop back towards normal values as s/he begins to respond to therapy. About 5-10 percent of neuroblastoma’s do not produce elevated VMA and HVA.
