Comparison of Citrate and Heparin Anticoagulation During Postdilution Hemodiafiltration (CITRA-HDF)

Hemodiafiltration (HDF) is an advanced renal replacement therapy combining diffusion and convection, allowing improved removal of middle and larger molecular weight solutes compared with standard hemodialysis. During extracorporeal circulation, blood contact with artificial membranes and tubing activates complement, platelets, leukocytes, and coagulation pathways, requiring anticoagulation during the procedure.

Unfractionated heparin is routinely used for anticoagulation during HDF. Regional citrate anticoagulation (RCA) is mainly used in patients at increased bleeding risk. Previous studies in hemodialysis have suggested that citrate anticoagulation may improve biocompatibility because many blood-material interactions are calcium- and magnesium-dependent. However, biocompatibility during HDF using citrate versus heparin anticoagulation has not been systematically investigated.

This prospective randomized crossover clinical trial will include 20 adult patients with end-stage kidney disease receiving maintenance postdilution hemodiafiltration three times weekly. Patients will be randomized to one of two anticoagulation sequences: heparin-citrate or citrate-heparin. Each participant will undergo two study HDF procedures separated by a one-week interval.

During heparin anticoagulation, unfractionated heparin will be administered according to body weight using standard clinical protocols. During citrate anticoagulation, 8% trisodium citrate infusion and calcium-free dialysate will be used, with continuous calcium chloride substitution adjusted according to ionized calcium levels.

Biocompatibility markers including complement activation marker C3a, platelet factor 4 (PF4), thrombin-antithrombin complex (TAT), blood cell counts, and coagulation parameters will be assessed before HDF, after 15 minutes, and at the end of the procedure.

Dialysis efficiency will be evaluated by measurement of reduction ratios and total removal of beta-2 microglobulin, phosphate, and urea using partial dialysate collection methodology.

Additional secondary outcomes include assessment of citrate, calcium, and magnesium kinetics during RCA-HDF, visual clotting score evaluation of the extracorporeal circuit, and optimization of citrate anticoagulation protocols during postdilution HDF.

The study may contribute to improved understanding of anticoagulation-related biocompatibility during HDF and support wider evidence-based use of regional citrate anticoagulation in chronic dialysis patients.