TFRC and Iron deficiency anemia: The prevalence of iron deficiency at baseline—according to the four definitions—is illustrated in Table 2: 26.8% (573/2141) of the participants had sTfR > 28.1 nmol/L, 9.3% (199/2141) had ferritin < 45 μg/L, 4.2% (90/2141) had ferritin < 30 μg/L, and 35.3% (755/2141) had sTfR–ferritin index > 1.5.