Inclusion Criteria:  Maintenance hemodialysis more than 3 months 3 sessions per week during 4 hours Hemodiafiltration process used with this patient on Lyon Sud Hospital Flow of the vascular access > 300 mL/min at least Age > 18 years Patient able to understand the study's goal  Exclusion Criteria:  Active infectious or inflammatory disease Active malignant disease Intestinal malabsorptive disease Polysulfone's dialysis membrane allergy Patient under guardianship and judicial protection Pregnant and breastfeeding woman Opposition to the study