High bilirubin levels may indicate a variety of problems with the liver, such as hepatitis or blockage of the liver's bile ducts. More infrequently hemolysis, the destruction of red blood cells, is a cause of high bilirubin, according to Mayo Clinic. High levels in newborns often indicates jaundice.
Normal bilirubin levels are 0.1 to 1 milligram per deciliter of total bilirubin, or 0 to 0.3 for direct, reports the Mayo Clinic. Bilirubin levels that are lower than normal do not necessarily indicate a medical issue. A deficiency in the enzyme that breaks down bilirubin is called Gilbert's syndrome. This syndrome is common and harmless, according to the Mayo Clinic.