NOTE: Ferritin is an acute phase reactant, low or normal ferritin levels may be seen in iron deficiency where there is inflammation, liver disease, metabolic syndrome, chronic alcohol use, malignancy, and some instances of immune compromise. If clinically indicated repeat with CRP level.
Normal iron stores
Serum ferritin 30–100 ug/L
Transferrin saturation ≥20%
CRP <5 mg/L
Trial of iron–no change in Hb or reticulocyte count
Iron deficiency
Serum ferritin <30 ug/L
Transferrin saturation <20%
CRP <5 mg/L
Trial of iron–increased Hb and reticulocyte count
Normal iron stores + acute phase response
Serum ferritin >30 ug/L
Transferrin saturation <20%
CRP >5 mg/L
Trial of iron–no change in Hb or reticulocyte count