In anemic ND-CKD patients, non-comparative studies have shown oral SI supplementation (30 mg/day), with or without ESAs, to be efficacious for the maintenance and/or improvement of Hb, ferritin, and TSAT concentrations through 3- to 18-month follow-up periods, whereas the incidence of gastrointestinal side effects was almost negligible (Supplementary Materials, Table S2). This evidence concerns the gene GSTM1 and chronic kidney disease.