End stage renal disease is a severe pathology in which some toxic waste and an excessive amount of water can accumulate in the human body with life threatening consequences. Maintenance hemodialysis is one of the possible treatment for this disease.

Hemodialysis filter the blood through a membrane according to a dialysis bath and so can be able to purify the blood of the toxic waste.

Otherwise, since the 1980s, the investigator know that patient in maintenance hemodialysis can have some deficiency in water soluble vitamins and trace elements. Mechanisms of the deficiency are multiple (a decreased of food intake, a diminution of the appetite, digestive malabsorption du to medics and comorbidities and loss in hemodialysis).

Impact of this deficiency have an important impact on vital prognosis for these patients. These nutrients are essential for AND synthesis, mechanism of inflammation, cells membranes synthesis, etc. DOPPs study in 2004 have shown a decreased of 16% in the mortality within 4 years with supplemented patients. Also, since this study, international recommendations were wrote in 2009, then in 2020, in order to supplement in vitamins and trace elements patients in maintenance conventional hemodialysis.

Despite these recommendations, some supplementary efforts are necessary, especially since online hemodiafiltration, a new process, is widely available and used in particular in Europe. This process combines 2 phenomena, diffusion and convection, through high-flux membranes. This process can remove a large quantity of molecule present in blood and especially the middle-molecule. In return, a more important quantity of water soluble vitamins and oligo-elements could be removed by this technique.

Also, the investigator would like to measure this loss of vitamins and trace-elements in patients with maintenance online post-dilution hemodiafiltration process with dialysate sample and blood concentrations measured (usual patient monitoring) during the session.

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

Maintenance hemodialysis patients who are treated in nephrology unit at Centre Hospitalier de Lyon Sud with online hemodiafiltration process