GSTM1 and chronic kidney disease: The Kidney Disease Outcomes Quality Initiative (K/DOQI) 2006 guidelines recommend iron therapy to maintain ferritin > 100 ng/mL and TSAT > 20% in non-dialysis chronic kidney disease (ND-CKD) patients16, while the Kidney Disease Improving Global Outcomes (KDIGO) 2012 guidelines recommend iron therapy in ND-CKD patients with TSAT < 30% and serum ferritin < 500 ng/mL if an increase in Hb levels is desired17.