HDF is a dialysis technique which involves diffusion and convection. HDF with high convection volume has consistently shown to improve survival in dialysis patients in number of robust RCTs. The precise reason of this survival benefit remains unclear. The investigators hypothesize that this survival benefit with high volume HDF is related to enhanced middle molecule clearance and hemodynamic stability. However, this relationship has not been studied so far. This observational study is aimed to understand the relationship between HDF convection volume with middle molecules (Beta 2-Microglobulin) clearance during HDF. Exploring the relationship of HDF volume with middle molecules clearance has significant clinical ramifications. Only a minority of patients are able to achieve target convection volume. Understanding these relationships can rationalize the HDF prescription from convection volume-based prescription to β2-Microglobulin clearance-based prescription which may be applicable to wider range of patients. The relationship between pre-dialysis β2-Microglobulin levels and RKF offers the prospect of dispensing with pre- and post-dialysis urea and creatinine measurements and interdialytic urine collections, currently necessary for estimating RKF, thus simplifying its estimation. β2-Microglobulin reduction ratio and its component pre and post-dialysis β2-Microglobulin levels could therefore provide a composite estimate of small and middle molecule clearance and RKF.