Translations:Vitamin B6/39/en

The end-product of vitamin B₆ catabolism is 4-pyridoxic acid, which makes up about half of the B₆ compounds in urine. 4-Pyridoxic acid is formed by the action of aldehyde oxidase in the liver. Amounts excreted increase within 1–2 weeks with vitamin supplementation and decrease as rapidly after supplementation ceases. Other vitamin forms excreted in the urine include pyridoxal, pyridoxamine and pyridoxine, and their phosphates. When large doses of pyridoxine are given orally, the proportion of these other forms increases. A small amount of vitamin B₆ is also excreted in the feces. This may be a combination of unabsorbed vitamin and what was synthesized by large intestine microbiota.