Indirect (Unconjugated) vs. Direct (Conjugated) Bilirubin
The bilirubin that is processed by your liver is “unconjugated,” which means it is not water-soluble (dissolvable in water). It is attached to an albumin-like protein in your blood that aids in transporting it to your liver. When the bilirubin is processed by your liver, it separates it from the albumin and links it to a sugar molecule, making it water-soluble. This enables it to combine with bile and go through your intestines.
The bilirubin that your liver converted is referred to as “conjugated” bilirubin. On your test results, it may be identified as “direct” bilirubin. That is so that this type may be immediately measured. Direct measurements of unconjugated bilirubin are not possible. It is calculated by deducting the amount of conjugated from the amount of total bilirubin in your blood. On your test results, “indirect” bilirubin may be used to describe unconjugated bilirubin.