Xanthurenic Acid

Optimal result: 0 – 0.96 mmol/mol creatinine

Genova Diagnostics

By Healthmatters Editorial Team

Peer-reviewed sources

Because this pathway is heavily dependent on vitamin B6, elevations of xanthurenic acid can reflect a functional need for vitamin B6.

Kynurenine pathway metabolites may also become elevated when there are needs for vitamin B3.

Elevations in urinary xanthurenic acid are seen with increased intake of tryptophan, and in high estrogen states. Pregnancy and oral contraceptive use is associated with elevated levels of urinary xanthurenic acid where a functional nutrient need for B-vitamins is pronounced.

Abnormalities in the kynurenine pathway have been associated with many clinical conditions including immune suppression, cancer, and inflammatory conditions. Administration of vitamin B6 can decrease xanthurenic acid excretion.

Xanthurenic acid is produced as part of the kynurenine pathway of tryptophan catabolism, along with kynurenic and quinolinic acid.

References:

- Brown R, Thornton MJ, Price J. The effect of vitamin supplementation on the urinary excretion of tryptophan metabolites by pregnant women. J Clin Invest. 1961;40(4):617- 623.

- Ciorba MA. Kynurenine pathway metabolites: relevant to vitamin B-6 deficiency and beyond. Am J Clin Nutri. 2013;98(4):863-864.

- Payne IR, Walsh EM, Whittenburg EJR. Relationship of dietary tryptophan and niacin to tryptophan metabolism in schizophrenics and nonschizophrenics. Am J Clin Nutr. 1974;27(6):565-571.

- Linkswiler H. Biochemical and Physiological Changes in Vitamin B6 Deficiency. Am J Clin Nutr. 1967;20(6):547-557.

- Luhby AL, Brin M, Gordon M, Davis P, Murphy M, Spiegel H. Vitamin B6 metabolism in users of oral contraceptive agents. I. Abnormal urinary xanthurenic acid excretion and its correction by pyridoxine. Am J Clin Nutr. 1971;24(6):684-693.

- Chiang EP, Selhub J, Bagley PJ, Dallal G, Roubenoff R. Pyridoxine supplementation corrects vitamin B6 deficiency but does not improve inflammation in patients with rheumatoid arthritis. Arthr Res Ther. 2005;7(6):R1404-1411.

- Yess N, Price JM, Brown RR, Swan PB, Linkswiler H. Vitamin B6 Depletion in Man: Urinary Excretion of Tryptophan Metabolites. J Nutr. 1964;84(3):229-236.

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