Jaundice - causes, treatment & pathology

Jaundice, which doesn’t have the most intuitive name, comes from the french jaunice, meaning

yellowing.

It’s also sometimes referred to as icterus though, the origin of which is even less intuitive,

coming from the thought that jaundice could once be cured by looking at a yellow bird,

the more you know!

Anyways, as you’ve probably gathered, jaundice involves someone taking on yellow pigments,

specifically in the skin and eyes.

The yellowing pigment is caused by a compound called bilirubin, a component of bile and

the main cause of bruises being yellow, and after its metabolism, the yellow-ness of urine

and brown-ness of feces.

So since bilirubin’s our main culprit of yellow-ness, it’s super important to know

where it comes from.

As red blood cells near the end of their lifespan—which is about 120 days—they’re eaten up or

phagocytosed by macrophages in the reticuloendothelial system, aka the macrophage system, where the

spleen plays the largest part, but it’s also made of parts of the lymph nodes.

K so first the macrophage eats up the blood cell, and hemoglobin is broken up into heme

and globin, the globin is further broken into amino acids.

The heme on the other hand is split into iron and protoporphyrin, protoporphyrin is then

converted into unconjugated bilirubin, or UCB.

Unconjugated bilirubin is the form of bilirubin that’s lipid-soluble, meaning it’s not

water-soluble, sometimes it’s also known as indirect bilirubin.

Albumin in the blood then binds to UCB and gives it a lift over to the liver where it’s

taken up by hepatocytes, where it’s conjugated by an enzyme called uridine glucuronyl transferase

(UGT), making it now water soluble.

At this point the conjugated bilirubin is secreted out the bile canaliculi where it