The Direct Bilirubin test is a blood test that measures the level of direct bilirubin, which is one of the byproducts of hemoglobin breakdown from red blood cells. Bilirubin is produced in the liver and is divided into two types: indirect (unconjugated) bilirubin and direct (conjugated) bilirubin. Direct bilirubin is water-soluble, which allows it to be eliminated from the body through bile. This test is used to assess the health of the liver and gallbladder and to diagnose conditions such as jaundice, which occurs when bilirubin levels accumulate in the blood. Elevated levels of direct bilirubin may indicate liver problems, such as hepatitis or bile duct obstruction. The direct bilirubin test is part of a group of tests that evaluate liver function and help determine possible causes of related symptoms.