How is bilirubin conjugated in the liver?

In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, first to bilirubin glucuronide and then to bilirubin diglucuronide, making it soluble in water: the conjugated version is the main form of bilirubin present in the “direct” bilirubin fraction.

What is the effect of the process of conjugation of bilirubin in the liver?

Conjugation is mandatory to render bilirubin aqueous soluble and facilitate its secretion across the canalicular membrane and excretion into bile. Bilirubin is conjugated within the hepatocyte to glucuronic acid by a family of enzymes, termed uridine-diphosphoglucuronic glucuronosyltransferase (UDPGT).

What happens conjugated bilirubin?

Conjugated bilirubin is excreted through the bile into the intestine, where it is deconjugated by a mucosal enzyme, β-glucuronidase, and reabsorbed into the enterohepatic circulation before it can be excreted with the stool.

How does bilirubin become conjugated?

In the bloodstream, unconjugated bilirubin binds to albumin to facilitate its transport to the liver. Once in the liver, glucuronic acid is added to unconjugated bilirubin by the enzyme glucuronyl transferase. This forms conjugated bilirubin, which is soluble.

Is conjugated bilirubin bound to albumin?

Bilirubin conjugated with glucuronic acid also binds to albumin but with much lower affinity. Another form of bilirubin (probably conjugated), very tightly (probably covalently) bound to albumin, has been described.

When does conjugated bilirubin need to be assessed?

When does conjugated bilirubin need to be assessed? Neonatal jaundice is commonly seen in newborns in the first few days of life, mainly due to increased bilirubin formation from break down of red blood cells and limited conjugation of bilirubin. Total bilirubin normally peaks at day 2-3 and should decline by day 4-5.