Bilirubin is a breakdown product of hemoglobin. Red blood cells contain hemoglobin, which is broken down into the components "heme" and "globin." Heme is converted into bilirubin. Albumin carries bilirubin to the liver, where most of it is conjugated with a glucuronide before it is excreted in the bile. Conjugated bilirubin is called "direct bilirubin;" unconjugated bilirubin is called "indirect bilirubin." Total bilirubin equals direct bilirubin plus indirect bilirubin.