Vitamin B6 is excreted in the urine as

Vitamin B6 is also known as Pyridoxine. The three organic compounds that are the vitamers of Vitamin B6 are pyridoxine (C ₈ H ₁₁ NO ₃ , molecular weight 169 g/mol), pyridoxal (C ₈ H ₉ NO ₃ , molecular weight 167 g/mol), and pyridoxamine (C ₈ H ₁₂ N ₂ O ₂ , molecular weight 168 g/mol). All the vitamers have a pyridine ring as their core.

The most biologically active form of vitamin B6 is Pyridoxal 5′-phosphate. Vitamin B6 acts as a coenzyme in enzymes that are important for the synthesis of neurotransmitters, hemoglobin synthesis as well as the metabolism of glucose, amino acid and lipid.

Vitamin B ₆ is absorbed in the small intestine (jejunum) by passive diffusion. The catabolic end-product of vitamin B ₆ that is excreted through the urine is 4-pyridoxic acid. The normal level of 4-pyridoxic acid in the urine is 128-680 nmol per nmol of creatinine.