There has clearly been a comprehensive workup done. The ultrasound and blood tests would rule out many of the major liver disorders.
However, I agree that the biopsy is the next step in the face of negative results. ALTs and ASTs in the hundreds are relatively high, and more serious liver causes - like an autoimmune etiology - needs to be ruled out.
Another GI opinion can be considered if the diagnostic pathway isn't clear.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_