Ferric Citrate for the Transition From CKD Stage 4/5 to CKD Stage 5D

It is the investigators hypothesis that participants treated with Ferric Citrate (FC) during the non-dialysis CKD stage (4/5) with sufficient duration prior to initiating RRT, will result in improved biochemical control of anemia (Hb, TSAT) and mineral metabolism (P, FGF23) and furthermore, will result in a reduced need for ESA and intravenous iron. The investigators further hypothesize that effective treatment of anemia and mineral metabolism with FC in the pre-dialysis and transition period will result in improved physical functioning, reduced hospitalization and reduced total cost of care when compared to participants receiving contemporaneously provided standard of care therapy.