2mg/dl urobilinogen in urine. bilirubin negative, what could this mean?

All laboratory results need to be interpreted in the clinical context and the doctor who ordered the tests is usually in the best position to do that. Talk to the doctor who ordered the tests. Having said that, your result is at the upper limit of normal. If you had any illness recently, you may wish to repeat the test in 3-4 months. Wish you good health!