The study includes 40 adults who have established CKD stages 3–5 and serum ferritin (SF) of less than 200 μg/L or transferrin saturation (TS) of less than 20% (or both); they were randomly assigned in a 1:1:1:1 ratio to 200 mg iron dextran, 200 mg iron sucrose, 200 mg iron isomaltoside, or 1000 mg iron isomaltoside. Here, TF is linked to chronic kidney disease.