Multicentre, open, prospective and interventional study investigating the CardioRenal device in capillary blood of patients.It will be conducted at multiple investigational sites.

Objectives are to assess the quantitative accuracy in freshly collected whole capillary blood from patients and healthy volunteers and to evaluate user proficiency. In order to gather a wide range of K+ concentrations, the study will be conducted both on patients or healthy volunteers and on dialysis patients.

The study includes 2 phases (calibration phase and comparison phase) where blood samples (capillary and venous) will be collected.Blood is taken from the subject by trained specialist staff. During the comparison phase, the subjects will be equipped with CardioRenal device and trained to do the self-test.

A subject's participation in this study (both calibration and validation phase) will consist of two interventional visits for hemodialysis patients and three interventional visits for other subjects.

Inclusion Criteria for subjects not on dialysis:

• Male/female subject, aged 18+ years ;
• Signing a written informed consent ;
• Willing to perform the self-test after viewing the instruction for use;
• Covered by Health Insurance System and / or in compliance with the recommendations of National Law in force relating to biomedical research.

Inclusion Criteria for hemodialysis patients:

• Male/female subject, aged 18+ years ;
• Medical history of dyskalemia ;
• Signing a written informed consent ;
• Willing to perform the self-test after viewing the instruction for use;
• Covered by Health Insurance System and / or in compliance with the recommendations of National Law in force relating to biomedical research.

Non-inclusion Criteria for subjects not on dialysis:

• Medical history of seizure (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) stage 4
• Raynaud syndrome
• Known evolutive cancers
• Subjects who are pregnant or breast-feeding
• 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
• Subject who, in the judgment of the Investigator, is likely to be non-compliant or uncooperative during the study, or unable to cooperate because of a language problem, poor mental development
• Subject who is prohibited from participation in the study after consulting the Ministry of Health National File (e.g. indemnities > 6000 euros for a 12-months period)

Non-inclusion Criteria for hemodialysis patients:

• Medical history of seizure (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) stage 4
• Raynaud syndrome
• Known evolutive cancers
• Subjects who are pregnant or breast-feeding
• 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
• Subject who, in the judgment of the Investigator, is likely to be non-compliant or uncooperative during the study, or unable to cooperate because of a language problem, poor mental development
• Subject who is prohibited from participation in the study after consulting the Ministry of Health National File (e.g. indemnities > 6000 euros for a 12-months period)