An Observational Prospective Cohort Study for Long-term Management of Hyperkalemia in Patients With Chronic Kidney Disease or Heart Failure

Inclusion Criteria: * Patients with hyperkalemia who meet the following criteria: 1\) Being treated with potassium binders for hyperkalemia at the time of enrolment, and having started receiving potassium binders within 6 months before enrolment * Having been diagnosed as CKD (≥stage 3b) or HF diagnosed by investigators, and as defined below: 1\) CKD is diagnosed based on the CKD guidelines issued by the Japanese Society of Nephrologyxxix as being either or both of condition 1 and 2 for ≥3 months 1-i) Clear signs of kidney impairment based on the results of urinalysis, imaging, blood test, or biopsy. Presence of proteinuria, especially more than 0.15 g/gCr (albuminuria more than 30 mg/gCr). 1-ii) GFR \<45 mL/min/1.73m2 2\) Patients with HFwill be enrolled if patients meet following criteria: 2-i) NYHA class II-IV, within 6 months 2-ii) Patients with a diagnosis or history of heart failure, hospitalization, and laboratory records of any of the following; NT-proBNP≥400 pg/ml or BNP≥100 pg/ml, or pathological findings such as abnormal cardiac function by UCG/CT/MRI/catheterization/nuclear medicine examination * Provision of signed, written, and detailed informed consent Exclusion Criteria: * Currently on any chronic RRT (including hemodialysis or peritoneal dialysis \>30 days, or kidney transplant) within 6 months before enrolment * Patients with acute kidney injury (AKI)\* within 6 months before enrolment * Patients with acute heart failure within 3 months before enrolment * Patients who received blood transfusion within 6 months before enrolment * Patients with active malignancy or whose life expectancy is less than 6 months * GI disturbance, chronic diarrhoea, or GI stoma if, as judged by the investigators, that condition or its treatment has an important impact on S-K values * Autoimmune disease if, as judged by the investigators, that condition or its treatment has an important impact on S-K values * Patients who are suspected, on the basis of laboratory data, to have pseudohyperkalemia (abnormality in the sample, a history of severe leukocytopenia or thrombocytopenia) * Patients with recent traumatic injury * Patients who are pregnant, lactating, or planning to become pregnant * Current participation in a clinical trials, i.e. an interventional studies * Presence of a condition that, in the opinion of the investigator, i) would places the subject at undue risk, or ii) would potentially jeopardizes the quality of the data to be generated, or iii) would prevent the patient from performing protocol-defined tasks for physical or mental reasons, or iv) would prevent the patient from understanding the contents of the self-administered questionnaire and responding to its questions on his/her own, or v) would, for some other reason, make the patient inappropriate for this study.