TF and anemia (phenotype): For scenarios in which ferritin level and transferrin saturation were concordantly low or normal, respondents correctly identified the cause with more than 93% accuracy: 321 of 325 respondents (98.8%) correctly attributed anemia to iron deficiency in the presence of a low transferrin saturation (6%) and a low ferritin level (11 ng/mL), and 303 of 325 (93.2%) correctly attributed anemia to an alternate cause in the presence of a normal transferrin saturation (30%) and a normal ferritin level (150 ng/mL) (Figure 2).