Inclusion Criteria:  Age ≥ 20 years old on the day of index discharge AKI develops during admission, as defined with KDIGO-AKI Guideline, namely, elevation of serum creatinine above 0.3mg/dL within two days, above 1.5 times baseline and ever receives dialysis during this index hospitalization. Patients who has KDIGO-AKI stage 2, 3 or who could wean from dialysis requiring AKI-D in the index hospitalization.  Exclusion Criteria:  Baseline estimated glomerular filtration rates (eGFR) less than 5ml/min/1.73m2 or greater than 90ml/min/1.73m2 according to MDRD equation after index discharge. Patients receive further re-dialysis within 90 days after index hospital discharge, who are withdrawal for AKI-D. (sensors) Previous gastrointestinal operations. Patients with major hemorrhage, as defined with acute hemorrhage and requirement of blood transfusion during index admission. Patients with a chronic lung disease requiring non-invasive or invasive positive pressure ventilation. Solid organ or hematological transplantation donors. Evidence of obstructive acute kidney injury. Systolic blood pressure < 110mmHg. Pregnant women