Does small amounts of bilirubin show up in urine if i haven't eaten in two days?

It still might.: High bilirubin can come from hemolysis of red cells, liver damage, or gallstones. So if a lot of your red cells are being destroyed, or you have a liver issue like cirrhosis, or hepatitis, or a history of gallstones, you can have at least some bilirubin in your urine, even if you didn't eat. In fact, not eating might cause it due to the liver using your reserves. If it persists, see your doctor.