In addition, the current definitions for iron deficiency are mainly based on ferritin and TSAT levels; however, other iron status parameters such as sTfR levels, percentage hypochromic red blood cells, or reticulocyte Hb content may help define the conditions better or evaluate the efficacy of iron therapy, although they are mostly used in the academic setting.81, 82, 83 Controversy also exists regarding how to manage iron metabolism in CKD and therefore management and guidelines among countries have differences (Table 4).78 This evidence concerns the gene GSTM1 and chronic kidney disease.