Total and direct bilirubin levels in blood are also measured as part of the liver function tests. Bilirubin is the chemical substance that gives bile, a fluid produced by the liver, its yellow-green color. Jaundice, the yellow discoloration of the skin seen in some types of liver disease, occurs because high levels of bilirubin accumulating in the blood lead to some of the substance becoming deposited in the skin. Bilirubin is produced from hemoglobin, which is released when red blood cells break down. The liver takes bilirubin and attaches conjugated sugar molecules to it so it can leave the body through the urine. This type of bilirubin is called conjugated direct (because it can be measured directly in a water solution) bilirubin. In liver disease, bilirubin levels in blood can become high. Measurements of total and direct bilirubin can be helpful in diagnosing specific liver problems