Can a total bilirubin level of 4.5 make someone have a change in mental status even with normal liver functioning?

Bilirubin. This answer would depend upon the underlying cause of the bilirubin elevation. It is certainly possible with cirrhosis and liver failure to have altered mental status. If there is an infection such as cholangitis (bile duct infection) it is also possible to have altered mental status. If it is due to a condition such as gilbert's syndrome then it is less likely.