Online hemodiafiltration (Ol-HDF) is increasingly being used for patients on chronic dialysis due to in its superiority compared with standard hemodialysis HDF. In addition to an excellent clearance of small molecules, oL-HDF has more advantages by providing both diffusion and convection modalities for an additional clearance of medium-size molecules. Furthermore, OL-HDF has been associated with not only better hemodynamic tolerance and biocompatibility , but may even include better survival.with reduction of proinflammatory cytokines and proinflammatory circulating cells , as well as with better control of B2MG levels .Ol-HDF is classified into 2 types according to the mode of addition of the substitution fluid: pre-dilution OL-HDF (pre-HDF) and post-dilution OL-HDF (post-HDF); Post-HDF was associated with significantly higher removal rates of β2-MG than HD. Postdilution HDF is the most effective way to maximize molecule clearance .Post-HDF was associated with significantly higher removal rate of α1-MG, and also significantly higher albumin leakage, than HD and pre-HDF. However, blood concentrations can be elevated using HDF, which can cause thrombosis. On the other hand, predilution HDF can resolve this problem but requires about three times more purified water than postdilution HDF and may not elicit maximal clearance.

Heparin is the most routinely used anticoagulant in hemodialysis. However, it exposes the patient to the risk of bleeding complications and can induce thrombocytopenia. Furthermore, long-term use of heparin induces biological and clinical complications (osteoporosis, dyslipidemia, hyperkalemia) . Regional citrate anticoagulation is a good alternative to heparin use in hemodialysis for patients with increased bleeding risk , but its implementation in bicarbonate hemodialysis (BHD) is laborious and cumbersome: severe side effects can occur due to citrate metabolism and difficulties in adaptation of calcium infusion into the venous line .Therefore, the use of citrate as a dialysis buffer instead of acetate has proven a safe alternative to acetate-containing bicarbonate dialysis and on-line hemodiafiltration without significant hypocalcemia or clinically important coagulation issues.The aim of the present study is the comparison of the patency of the dialyzer ,the quality of life and blood parameters between pre and potdiltuiotn Ol-HDF with citrate dialysate (CD). No study to date has previously compared the use of citrate dialysate between these two modalities in oL-HDF.

Inclusion Criteria:

• Stable condition
• Having been under HD for at least three months
• he vascular access should have blood flow ≥ 300 mL/min.

Exclusion Criteria:

• no heparin use during HD
• refusal to participate,
• intolerance or allergy to citrate
• concurrent infection
• poor life expectancy due to metastatic cancer, severe cirrhosis and AIDS.
• patients vascular access modification,
• patients affected by chronic liver disease, active neoplastic or inflammatory disease were excluded as well as patients receiving immunosuppressive or anti-inflammatory drugs.