Does ferritin increase during chronic inflammation even when usable iron is restricted?

Ferritin is a well-established positive acute-phase reactant (APR), meaning its serum concentration increases in response to systemic inflammation, often independent of a patient's actual total body iron stores. In clinical practice, this elevation is a hallmark of chronic inflammatory states, including chronic kidney disease (CKD), rheumatoid arthritis, and inflammatory bowel disease.

Clinical and mechanistic evidence

The rise of ferritin during inflammation is driven by a complex interplay of cytokines and iron-regulating hormones:

• Cytokine-Induced Synthesis: Pro-inflammatory cytokines, specifically Interleukin-6 (IL-6), IL-1, and TNF-α, directly stimulate the liver to increase the production of ferritin. This is mediated by the NF-κB signaling pathway, which binds to the promoter regions of ferritin genes to induce transcription.
• The Hepcidin-Ferroportin Axis: Inflammation triggers the release of hepcidin, the master regulator of iron. Hepcidin binds to and degrades ferroportin, the only known cellular iron exporter. This effectively "locks" iron inside macrophages and hepatocytes.
• Functional Iron Restriction: As iron is trapped within these cells, it is sequestered as intracellular ferritin. This creates a clinical paradox: serum ferritin levels rise (due to increased synthesis and leakage from cells), while the circulating iron needed for essential processes like erythropoiesis (red blood cell production) remains critically low.

Clinical implications

Because ferritin levels are artificially inflated by inflammation, standard diagnostic thresholds for iron deficiency are often insufficient. In inflammatory conditions, a patient may be functionally iron deficient even with a ferritin level as high as 100 µg/L or more. To accurately assess iron status in these patients, clinicians frequently evaluate ferritin alongside C-reactive protein (CRP) or utilize markers less affected by the acute-phase response, such as soluble transferrin receptor (sTfR).

Bottom line

Ferritin is a robust acute-phase reactant that rises during chronic inflammation. This elevation occurs through cytokine-driven synthesis and hepcidin-mediated sequestration, which can lead to high ferritin levels even when usable iron is functionally restricted from systemic circulation.