Table 2.

Clinical indicators for monitoring iron deficiency and iron deficiency anemia.

Condition	Physiology	Current test	Proposed test
Mild ID	Mobilized available iron	↓Serum iron, ↓SF	↓Hepcidin, ↓CHr, Perl’s staining (−)
Moderate ID	Increased iron delivery	↑TIBC, ↓TSAT, ↑sTfR	↓Hepcidin, ↓CHr, Perl’s staining (−)
Moderate to severe ID	Altered RBC morphology	↓MCV, ↑ZPP	↓Hepcidin, ↓CHr, Perl’s staining (−)
IDA	Impaired RBC production	↓Hb	↓↓Hepcidin, ↓CHr, Perl’s staining (−)

ID, iron deficiency; IDA, iron deficiency anemia; MCV, mean corpuscular volume; RBC, red blood cell; SF, serum ferritin; sTfR, soluble transferrin receptor; TIBC, total iron binding capacity; TSAT, transferrin saturation; ZPP, zinc protoporphyrin; Hb, hemoglobin; CHr, reticulocyte hemoglobin concentration; Perl’s staining, Perl’s staining of bone marrow for iron. ↑, increased; ↓, reduced; (−), negative. Data adapted from Baker et al. (2010), Wilson and Sloan (2015), and Georgieff (2017).