Bilirubin is a biochemical parameter of your liver function test. Your doctor uses this tool to diagnose liver disease. In the human body, bilirubin is a waste product of your hemoglobin produced during the red blood cells breakdown in the spleen. Although bilirubin does not have a specific function, it is generally a component of bile juice. It is also called a bile pigment, which is yellow in color. There are two forms of bilirubin in our blood. One is unconjugated bilirubin, which forms during the breakdown of red blood cells, and the other is conjugated, which starts during metabolism in the liver. The unconjugated bilirubin is a catabolic product of red blood cells. This non-conjugated compound is also known as indirect bilirubin. Some possible reasons or diseases associated with unconjugated hyperbilirubinemia – 1. Hemolytic anemia 2. Neonatal Jaundice 3. Genetic factors 4. Drug induced unconjugated hyperbilirubinemia On the other hands, Conjugated bilirubin is generally formed after the glucuronidation of the unconjugated bilirubin. The conjugation process occurs in your liver and converts your unconjugated bilirubin into conjugated bilirubin. This type of glucuronidation compound is also known as direct bilirubin. In simple words, direct bilirubin means conjugated bilirubin. The elevated conjugated bilirubin indicates Conjugated hyperbilirubinemia. This condition is most commonly seen in cholestatic liver disease. Cholestatic is a medical condition where the flow of bile juice gets reduced or stopped. You may have this cholestatic liver disease in two forms – Intrahepatic and extrahepatic obstruction. In this article, we will discuss bilirubin, metabolism of bilirubin, normal range of bilirubin, and its clinical relevance. Further, we will also know the difference between conjugated and unconjugated bilirubin.