Saturday, 28 July 2018

VMA (vanillylmandelic acid or DL-4-hydroxy-3-methoxymandelic acid)

It «is a chemical intermediate in the synthesis of artificial vanilla flavorings [1] and is an end-stage metabolite of the catecholamines, epinephrine, and norepinephrine. (...). VMA is found in the urine, along with other catecholamine metabolites, including homovanillic acid (HVA), metanephrine, and normetanephrine. In timed urine tests, the quantity excreted (usually per 24 hours) is assessed along with creatinine clearance, and the quantity of cortisols, catecholamines, and metanephrines excreted is also measured. Urinary VMA is elevated in patients with tumors that secrete catecholamines [2]. These urinalysis tests are used to diagnose an adrenal gland tumor called pheochromocytoma, (...). These tests may also be used to diagnose neuroblastomas [or other neuroendocrine tumors (e.g., ganglioblastoma, ganglioneuroma)], and to monitor treatment of these conditions [3].» Catecholamines «are released into the blood during times of physical or emotional stress, which are factors that may skew the results of the test [3].»
«The reference ranges of VMA in children are as follows [Burris, 2006, McPherson, 2011, and Wallach, 2011, cited by 4]:
  • Younger than 1 year: <27 mg/g creatinine;
  • Age 1-2 years: <18 mg/g creatinine;
  • Age 2-4 years: <13 mg/g creatinine;
  • Age 5-9 years: <8.5 mg/g creatinine;
  • Age 10-14 years: <7 mg/g creatinine.
The reference range in persons aged 15 years and older is 2-7 mg/24 hours [4].»
«In the evaluation of pheochromocytoma, vanillylmandelic acid is now considered the least-specific test for catecholamine metabolites, with a false-positive rate greater than 15%. Measurement of metanephrine, an intermediate metabolite between epinephrine and vanillylmandelic acid, is now considered the most sensitive and specific test for pheochromocytoma [4].»
Chemical formula: C9H10O5.
Bibliographic references:
[1] Fatiadi A, Schaffer R. An Improved Procedure for Synthesis of DL-4-Hydroxy-3-methoxymandelic Acid (DL-"Vanillyl"-mandelic Acid, VMA). Journal of Research of the National Bureau of Standards - A. Physics and Chemistry. 1974;78A(3):411–412. Available at: https://doi.org/10.6028/jres.078A.024.
[2] Magera MJ, Thompson AL, Matern D, Rinaldo P. Liquid chromatography-tandem mass spectrometry method for the determination of vanillylmandelic acid in urine. Clin Chem. 2003 May;49(5):825-6. Available at: https://doi.org/10.1373/49.5.825.
[3] Vanillylmandelic acid. En.wikipedia.org. https://en.wikipedia.org/wiki/Vanillylmandelic_acid. Published 2018. Accessed July 28, 2018.
[4] Lee A, Van Durme DJ. Vanillylmandelic Acid (VMA): Reference Range, Interpretation, Collection and Panels. Emedicine.medscape.com. https://emedicine.medscape.com/article/2089620-overview#a1. Published 2014. Accessed July 28, 2018.