Hep25, Ferritin, and Hep25/Ferritin levels and correlations among GDF15, EPO, and sTfR in CDA I patients. (A) Hep25, (B) Ferritin, and (C) Hep25/Ferritin levels in serum from healthy volunteers (HV) and patients with CDA I are shown as open circles with mean values (bars). *P < .05. Correlations of Hep25, Ferritin, and Hep25/Ferritin with (D-F) GDF15, (G-I) EPO, or (J-L) sTfR levels in CDA I patients are shown. Trend lines and statistical values (r and P) are included. NS indicates not significant.