Bilirubin in the intestinal tract

Urobilinogen is excreted mostly in the feces, but a small fraction is absorbed from the colon, enters the portal circulation, is removed by the liver, and is secreted into bile. That which is not removed from the portal blood by the liver enters the systemic circulation and is excreted by the kidneys. Urobilinogen excretion in urine normally amounts to 1-4 mg per 24 hours, as opposed to the 40-280 mg (67 70 /umol) excreted in feces. 

Lack of urobilinogen in the urine and feces indicates biliary obstruction stools are whitish ( clay-colored ) owing to the absence of bile pigment. Urinary and fecal urobilinogen excretion increases in hemolytic anemia. 

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