Why can ferritin be misleading in iron studies during infection or inflammation?

• A. Ferritin is an acute-phase reactant and can be elevated during inflammation, masking iron deficiency.
• B. Ferritin directly measures iron stores unaffected by inflammation.
• C. Ferritin decreases during infection, accurately indicating iron deficiency.
• D. Ferritin is unrelated to iron status.

Answer: (A)

Ferritin can be misleading during infection or inflammation because it acts as an acute-phase reactant. Inflammatory signals, especially IL-6, stimulate the liver to produce ferritin and other acute-phase proteins, so serum ferritin levels rise regardless of actual iron stores. This means you can have low iron stores with a normal or high ferritin if inflammation is present, masking iron deficiency. To interpret iron status accurately in the setting of inflammation, clinicians consider inflammatory markers like CRP and may look at other iron indices such as transferrin saturation or soluble transferrin receptor, which are less affected by inflammation.