In several case series on ND-CKD patients (mostly with mild anemia), oral SI (30 mg/day), with or without ESA, was shown to be efficacious in maintaining and/or increasing Hb, ferritin and TSAT levels during different follow-up periods (from 3 to 24 months), with virtually no gastrointestinal side effects (Supplementary material, Table S2). This evidence concerns the gene GSTM1 and anemia (phenotype).