Hb measurement is relatively inexpensive, and it is considered the most reliable indicator of anemia by the WHO.1,2 Although hematocrit (i.e., the volume percentage of red blood cells in the total blood volume) is a less accurate anemia marker,3 it is still used in several countries, and conversion formulas between hematocrit and Hb are available.3 This evidence concerns the gene GSTM1 and anemia.