Last reviewed 01/2018

Urobilin is a bile pigment derived from bilirubin via the intermediate urobilinogen. It is water soluble and imparts a brown colour to faeces.

Urobilinogen is formed:

  • by partial oxidation of urobilinogen during transit along the bowel
  • by oxidation within urine of urobilinogen

Hence, urobilin is found within both faeces and urine. Urinary losses may be up to 5mg/day in a healthy adult.