Table 1.

Diagnostic markers for the diagnosis of different types of inflammatory anemia.

Marker	Anemia of Inflammation	Anemia of Inflammation plus Iron Deficiency Anemia	Limitations/Comments
Bone marrow iron staining	Normal–Elevated	Normal–Reduced	Gold standard Invasive method, not routinely used
Serum Iron	Low	Low	Underlies diurnal variations
Ferritin	Elevated	Reduced–Normal–Elevated	Most commonly used marker Ferritin is an acute phase protein and does not accurately reflect iron status during inflammation Ferritin < 30 ng/mL always associated with true iron deficiency
Transferrin	Normal–Reduced	Normal–High
Tf-Sat	Low	Low	Dependent on iron and transferrin levels
sTfR	Normal–Elevated	Elevated	Good marker for needs of iron for erythropoiesis in absence of inflammation Values affected by inflammation and ESA application
sTfR/log Ferritin	Normal	Elevated	Used for differentiation, but there is a lack of a prospective study
Hepcidin	Elevated	Normal–Reduced	Expression is more affected by iron deficiency (suppressing) than by inflammation Not standardized Weak correlations in CKD patients Possible predictive parameter for success of iron and/or ESA treatment
Erythroferron	Not known	Not known	Not standardized Higher ERFE levels in CKD patients Positively correlated with serum erythropoietin and negatively with hemoglobin
MCV/MCH	Normal	Normal–Reduced	If reduced, indication of iron deficiency
Reticulocyte Hb content	Normal–Reduced	Reduced	Indicated insufficient iron availability for erythropoiesis, not prospectively studied
Hypochromic RBC	Normal	Normal–Elevated	Related to MCV, as a sensitive marker for iron availability for erythroid progenitors Cut-off values are different between different machines
CRP	Increased	Increased	Non-specific inflammatory marker Iron–independent parameter Correlation with severity of anemia
IL6	Increased	Increased	Non-specific inflammatory marker Iron–independent parameter