Total bilirubin 4.5. direct bilirubin 0.9. all other liver functioning tests are normal. why?

See below: Increased indirect bilirubin caused by overproduction of bilirubin ( breakdown product of red blood cells), reduced bilirubin uptake, or impaired bilirubin conjugation. Many causes, but in absence of other symptoms and a history of elevated bili in past this is likely a benign genetic disorder. However, there are other potential causes and you should see your doc to make sure.