The investigators hypothesize that the extent of sulfation of toxic BAs and their urinary elimination can be used as a biomarker to predict the severity and prognosis of hepatobiliary diseases. The investigators rationale in this project is that the discovery of biomarkers specific to liver injury would provide the foundation for a specific and non-invasive tool to evaluate disease prognosis, determine patients with higher risk of developing end-stage liver diseases, and determine patients with higher risk of recurrence of hepatobiliary complications after liver transplant.