I don't either, it is when it is high its a worry, high billirubin levels can cause jaundice, also a indicater of Pancreas, gall bladders, bile blocks, Your ok!
I don't think a low T Bilitubin is of much significance
"There is virtually no significance with a lowered T. bilirubin with the exception of possible seconday aplastic anemia"
http://www.easyhealthzone.com/Total_Bilirubin_s/64.htm
Ask the doc who ordered the tests..