In 2012, the KDIGO guideline recommended that oral iron therapy for 1–3 months be applied before the start of ESA treatment until the Hb falls to below 100 g/L, a near-normal correction of anemia to a Hb target of ≤115 g/L, that ESAs not be used to intentionally maintain the Hb concentration above 130 g/L, and that individualization of treatment be applied (3). Here, GSTM1 is linked to anemia (phenotype).