Inclusion Criteria:  Adults (Age Over 18 yo) Healthy volunteers Chronic Hemodialysed patients Pre-dialysis patient, taken off after the long interdialytic interval (> 2 days) AND with a K+ > 5.0 mmol/L just before starting the dialysis session (screening checked on venous or arterio-venous blood sample) Post-dialysis, in patients treated with a 2 mmol/l dialysis bath AND with a K+ < 3.5 mmol/L at the end of the dialysis session (screening checked on venous or arterio-venous blood sample)  Exclusion Criteria:  No consent Age <18 yo Medical history of crisis (epilepsy) Known inherited hemolytic anemia Autoimmune hemolytic anemia Infectious Hemolytic anemia Prosthetic Cardiac valves Hemolytic uremic syndrome Peripheral edema Dehydration Peripheral Arterial Obstructive Disease (PAOD) Raynaud syndrome Known evolutive cancers Vulnerable patients, patients deprived from liberty and patients with a physical or mental state altered by disease, age or disability which impacts their ability to defend their interests and for which protection measures are taken