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Vanillylmandelic acid in the urine
Last reviewed: 08.07.2022
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The reference values (norm) of excretion in the urine of vanillilmandelic acid are up to 35 micromol / day (up to 7 mg / day).
On the function of the adrenal medulla can be judged by examining the content in the urine of vanillilminal acid - the end product of tissue metabolism of dopamine.
Normally, only about 1% of the total number of catecholamines released during the day by the adrenal glands is excreted unchanged in the urine (adrenaline 0.36-1.65%, norepinephrine 1.5-3.3%), while in the form of vanillylmandelic acid - up to 75%. From the clinical point of view, the determination of vanillylmandelic acid in the urine especially helps in the diagnosis of pheochromocytoma and neuroblastoma.
It should be remembered that up to 50% of studies can give false-negative results, therefore it is recommended to determine vanillmindalic acid in freshly harvested urine immediately after the hypertensive crisis.
The sensitivity of this test for the diagnosis of pheochromocytoma is 28-56%, specificity is 98%.
Approximately 15-20% of patients with neuroblastoma have a normal level of vanillylmandelic acid in the urine, but the content of metanephrine and normetanephrine is increased, so it is necessary to investigate all these metabolites.