Continuing Sodium Zirconium Cyclosilicate (SZC) After Discharge Study

This is a Phase 4, randomised, controlled, open-label, parallel-group, multicentre study in participants with CKD treated for HK whilst in hospital. * Participants from 30 to 50 sites in 4 to 7 countries will be screened for enrolment. In total, up to a maximum of 163 participants will be enrolled, resulting in approximately 130 participants discharged and randomised and 104 evaluable participants (52 per arm). * The study plans to enrol approximately equal numbers of participants with mild HK (K+ between \> 5.0 and ≤ 5.5 mmol/L) and with moderate/severe HK (K+ between \> 5.5 and ≤ 6.5 mmol/L), with a minimum of 30% of the enrolled participants in either group. * During the in-hospital phase, participants will be treated with SZC as per local label, starting at baseline and based on local K+ measurement obtained within 24 hours of treatment initiation:). * Participants with HK (K+ between \> 5.0 and ≤ 6.5 mmol/L): 1. stop current K-binder if any 2. start SZC correction dose (note: participants currently on SZC should continue SZC correction dose, up to 72 hours). * Participants currently receiving any treatment for the current episode of HK and are already NK at baseline (K+ ≤ 5.0 mmol/L): 1) stop any current K-binder, 2) start SZC maintenance dose (note: participants currently on SZC maintenance dose should continue SZC maintenance dose). * All treatment decisions, including modification of the ongoing therapy for HK must be based on the investigator's medical judgement of the participant's best interest. * At discharge, NK participants who have been treated with SZC for between 1 and 21 days whilst in hospital and are started on SZC maintenance dose will be randomised in a 1:1 ratio to one of the following arms: * Arm A: Participants discharged with SZC, as per local label, to manage HK until the end of the outpatient phase * Arm B: Participants discharged with SoC, as per local practice, to manage HK until the end of study. Note: Participants intended to be discharged with a K+ binder (as per the site routine medical practice) will not be randomised and will be discontinued from the study. Still, participants randomised into Arm B may have a K-binder prescribed at Day 7 post-discharge, (or after Day 7 post-discharge), to treat confirmed HK or in case there is an increase in K+ level since discharge that, in the investigator's opinion, requires therapy. * The total duration of the study for each participant will be up to approximately 6 months. * Study visit schedule is as follows: In-hospital phase: - The screening visit will occur while the participant is at the hospital (up to 21 days before discharge; medical monitor's approval may be sought for allowing longer duration hospital stays for specific participants) in order to check eligibility criteria * Inpatient phase: o The baseline visit (can occur the same day as the screening visit) where treatment with SZC will be initiated o The discharge visit, 1 to 20 days after baseline; medical monitor's approval may be sought for allowing longer duration hospital stays for specific participants). Randomisation will occur at day of discharge. * Outpatient phase: - Visits will occur at 7, 30, 60, 90, 120, 150, and 180 (EOT, End of Trial) days after randomisation. Only visits at 7, 90 and 180 days after randomisation will be on-site visits, the remaining being telephone visits. If dose titration occurs at any time during the outpatient phase, unscheduled dispensation visits will be performed. Follow-up phase: - A follow-up on-site visit (end of study visit) will occur approximately 7 days after EOT. • Data will be collected at on-site visits, via telephone visits and medical chart reviews. • An adjudication committee will be involved in the study.