Serum ferritin concentrations in anemic patients. IDA (iron-deficiency anemia) (n = 48) and ACD (anemia of chronic disease) (n = 64). Those patients who had depleted iron stores together with an infectious disease, a chronic inflammatory disease, or a nonhematological malignancy were assigned to the COMBI group (n = 17). The lower reference limits of the serum ferritin assay are indicated separately for male (♂) and female (♀) subjects by horizontal bars.