In China, the estimated prevalence of patients with ESRD receiving PD or maintenance HD increased from 51.7 per million population (pmp) at the end of 2007 to 79.1 pmp at the end of 2008. Theranova 400 is designed to deliver the performance of hemodiafiltration (HDF) using standard hemodialysis (HD) equipment and treatment mode, including HD machines, disposables, blood and dialysate flows, length of treatment and frequency of treatment. Theranova 400 utilizes a Medium Cut-Off (MCO) membrane with extended permeability for middle solutes to closely modulate the removal function of the kidney without the complexity of HDF. The primary objective of the study is to demonstrate non-inferiority of the Theranova Dialyzer in hemodialysis (HD) mode compared to hemodiafiltration (HDF), using FX 800 in HDF mode. Comparison of the study arms over time will be used to support the safety of Theranova 400 by demonstrating stable serum albumin levels, as well as support the dialyzer's efficacy to significantly remove serum middle molecules.