In obstructive jaundice, is urobilinogen excretion increased or decreased?

In obstructive jaundice, the excretion of urobilinogen is decreased. This condition arises when there is a blockage in the bile duct system, preventing bile from reaching the intestines. Since bilirubin is conjugated in the liver and excreted into the bile, any obstruction results in less bilirubin being converted to urobilinogen by intestinal bacteria. As a consequence, since the pathway for producing and excreting urobilinogen is hindered, the overall levels of urobilinogen in the urine will be reduced.

This contrasts with conditions such as hemolytic anemia, where urobilinogen would typically be increased due to higher bilirubin production from the breakdown of red blood cells. Therefore, in the case of obstructive jaundice, the blockage leads to a significant decrease in urobilinogen excretion.