The normal range for bilirubin levels in the blood is 0.1 to 1 milligram per deciliter of total bilirubin, notes Mayo Clinic. The normal range for direct bilirubin in the blood is from 0 to 0.3 milligrams per deciliter. Test results may vary slightly for children and women.
A lower-than-usual bilirubin level is typically of no consequence, notes Mayo Clinic. However, elevated levels of bilirubin in the blood may indicate the presence of liver damage or diseases of the liver that cause the liver to fail to clear bilirubin properly from the body. This may be due to a blocked bile duct or Gilbert’s syndrome, which occurs when the body is deficient in an enzyme needed to break down bilirubin.