bili-, bil- +
(Latin: bile; which is a digestive juice secreted by the liver, stored in the gallbladder, and aids in the digestion of fats)
2. A coloring matter found in the feces, a product of the alteration of the bile pigments in the intestinal canal; identical to hydrobilirubin (body formed from bilirubin*, identical with urobilin*).
*Bilirubin is a pigment produced when the liver processes waste products. A high bilirubin level causes yellowing of the skin.
*Urobilin is also a yellow pigment identical with hydrobilirubin, abundant in the highly colored urine of fever, and also present in normal urine.
Urobilin is a constituent of the brown pigment found in feces; which is derived from bilirubin by reduction due to bacteria in the intestine.
2. A chromogen formed in the intestine from the breakdown of bilirubin; yields urobilins on oxidation; some is excreted in the feces and some is resorbed and excreted in bile or urine.
Some is excreted in the feces where it is oxidized to urobilin. Some is reabsorbed and re-excreted in the bile as bilirubin; while at times, it is re-excreted in the urine, where it may be later oxidized to urobilin.