In cases of extravascular hemolytic anemias, is urobilinogen excretion increased or decreased?

In extravascular hemolytic anemias, urobilinogen excretion is typically increased. This phenomenon occurs due to the accelerated breakdown of red blood cells, resulting in the release of hemoglobin into the bloodstream. As the hemoglobin is metabolized, it is converted to bilirubin, which is then processed by the liver.

In cases of hemolysis, particularly when red blood cells are destroyed outside the blood vessels (such as in the spleen or liver), the excess bilirubin produced overwhelms the liver's ability to conjugate it, leading to higher levels of unconjugated bilirubin entering the intestines. Once in the intestines, bilirubin undergoes further transformation by intestinal bacteria into urobilinogen.

Since extravascular hemolytic anemia leads to increased red cell destruction, it consequently results in elevated production and subsequent excretion of urobilinogen, making the correct answer reflect that urobilinogen excretion is increased in these conditions. The enhanced breakdown of red blood cells distinctly contributes to this observed increase, highlighting the relationship between hemolysis and bilirubin metabolism in the body.