What is the end product of heme degradation by macrophages?

The end product of heme degradation by macrophages is bilirubin. When hemoglobin is broken down, particularly during the phagocytosis of aged or damaged red blood cells, heme is released. Macrophages then convert heme to biliverdin through the action of the enzyme heme oxygenase. Biliverdin is subsequently reduced to bilirubin by biliverdin reductase.

Bilirubin, a yellow compound, then enters the bloodstream where it is transported to the liver. In the liver, bilirubin undergoes further metabolism, being conjugated with glucuronic acid to form conjugated bilirubin, which is more water-soluble and can be excreted into bile.

This process is critical for the recycling of iron and for the proper clearance of senescent red blood cells from circulation. Understanding this pathway is important in clinical contexts, particularly regarding conditions like jaundice, where bilirubin levels in the blood are elevated.

The other options do not pertain to the final product of heme degradation by macrophages. Hematocrit refers to the proportion of blood volume that is made up of red blood cells, urobilinogen is a product of bilirubin metabolism occurring in the intestines, and ferrochelat