Mass Spectrometry

Vanillylmandelic acid (VMA) is the final metabolite of epinephrine and norepinephrine. Neuroblastoma, pheochromocytoma, and other neuroendocrine tumors can produce large amounts of catecholamines, resulting in markedly elevated VMA levels. Therefore, measurement of VMA can be used to screen for pediatric catecholamine-secreting tumors, support the diagnosis of neuroblastoma, and monitor the treatment of patients with neuroblastoma.
Creatinine concentration can not only be used to assess glomerular filtration efficiency but also to normalize the concentrations of other analytes in random urine samples. The VMA concentration measured in a random urine sample is divided by the creatinine concentration to obtain the VMA-to-creatinine ratio.