TFRC and Iron deficiency anemia: The outcomes that were examined through meta-analyses were hemoglobin, anemia, serum ferritin, serum copper, iron deficiency, serum transferrin receptor (sTfR), hematocrit, C-reactive protein (CRP), erythrocyte superoxide dismutase (eSOD), zinc protoporphyrin (ZPP), serum total cholesterol, lactulose:mannitol molar ratio, and serum iron concentration.