[1] About half of the urobilinogen formed is reabsorbed and taken up via the portal vein to the liver, enters circulation and is excreted by the kidney.

The urobilinogen in the intestine is directly reduced to brownish colour stercobilin, which gives the feces their characteristic color.

In biliary obstruction, below-normal amounts of conjugated bilirubin reach the intestine for conversion to urobilinogen.

With limited urobilinogen available for reabsorption and excretion, the amount of urobilin found in the urine is low.

Low urine urobilinogen may result from complete obstructive jaundice or treatment with broad-spectrum antibiotics, which destroy the intestinal bacterial flora (obstruction of bilirubin passage into the gut or failure of urobilinogen production in the gut).