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Bilirubin production
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Bilirubin is the yellow pigment the body makes as it breaks down old red blood cells, and about 80% comes from hemoglobin, the protein those cells use to carry oxygen, and from erythroid cells destroyed early.
The breakdown happens mainly in the spleen and in other parts of what is called the reticuloendothelial system, the cells in charge of clearing out what is old. There, an enzyme called heme oxygenase frees the iron from heme, the part of hemoglobin that holds it, and leaves a green pigment, biliverdin. Right after that another enzyme, biliverdin reductase, turns that green into bilirubin, a yellowish orange: it is a red pigment that comes apart and passes through green before settling on yellow.
One important detail remains. Bilirubin does not dissolve in water, and blood is water, so it travels stuck to albumin, a protein that carries it.
In brief
About 80% of bilirubin comes from the hemoglobin of aging red blood cells and from erythroid cells destroyed early.
In the spleen and other parts of the reticuloendothelial system, heme oxygenase frees the iron from heme and leaves biliverdin, a green pigment.
Biliverdin reductase then converts that green pigment into bilirubin, which is yellowish orange.
A red pigment that comes apart and passes through green before settling on yellow.
It does not dissolve in water and travels through the blood bound to albumin.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Bilirubin, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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