Bilirubin Metabolism and Pathogenesis of Jaundice

Conjugation of Bilirubin in the Liver

Bilirubin is a yellow pigment derived from the breakdown of hemoglobin in red blood cells. It is transported to the liver, where it undergoes conjugation to become water-soluble. This conjugated bilirubin is then excreted into the bile and eliminated through feces.

Overview of Bilirubin Metabolism

Hemoglobin degradation releases bilirubin.
Unconjugated bilirubin binds to albumin for transport to the liver.
Hepatic enzymes conjugate bilirubin, making it water-soluble.
Conjugated bilirubin is secreted into bile ducts and intestines.

Pathogenesis of Jaundice

Jaundice occurs due to abnormal bilirubin metabolism or excretion, leading to excessive accumulation in the blood. It can be classified into three types:

Pre-hepatic jaundice: Increased bilirubin production due to hemolysis.
Hepatic jaundice: Liver dysfunction impairing bilirubin conjugation.
Post-hepatic jaundice: Obstruction in bile excretion.

Clinical Significance

Early diagnosis and treatment of jaundice are crucial in preventing complications such as hepatic failure and kernicterus. Common diagnostic tests include serum bilirubin levels, liver function tests, and imaging studies.