Anaemia of chronic inflammation: IL-6, hepcidin and locked-away iron
- Mechanism
In long infections, autoimmune disease or cancer, the body hides iron from microbes. Red cell production falls even though stores are full.
What it is
Anaemia of chronic inflammation (anaemia of chronic disease) is the commonest anaemia in hospitalized patients. It accompanies chronic infections (osteomyelitis, endocarditis, tuberculosis), immune disorders (rheumatoid arthritis, inflammatory bowel disease) and cancers. Inflammatory cytokines, chiefly IL-6, raise hepatic hepcidin, which degrades ferroportin and traps iron in macrophages and enterocytes. Erythropoietin is also inappropriately low and progenitors respond poorly, so a mild normocytic or slightly microcytic anaemia develops despite plentiful stored iron.
Step by step
- A chronic infection, autoimmune disease or tumour keeps macrophages and lymphocytes producing cytokines.
- IL-6 induces hepcidin synthesis in hepatocytes.
- Hepcidin binds ferroportin, which is internalized and destroyed: iron stays in macrophages and enterocytes.
- Little iron reaches erythroid precursors; cytokines also suppress erythropoietin and progenitor growth.
- Mild anaemia develops and persists while the inflammation lasts.
Clinical notes
- Mild anaemia in a patient with active rheumatoid arthritis, tuberculosis, chronic osteomyelitis or cancer.
- Only control of the underlying disease reliably corrects it; erythropoietin helps some patients with cancer or kidney disease.
- Iron deficiency can coexist, for example with GI bleeding in inflammatory bowel disease.
In the lab
- Iron studies, ferritin (which is also an acute-phase protein), C-reactive protein; marrow iron stain if unclear.
Test yourself
Think of the answer, then tap the question to see it.
Which cytokine drives hepcidin production in anaemia of inflammation?
Interleukin-6.
How does hepcidin limit iron availability?
It binds ferroportin and causes its degradation, so macrophages and enterocytes cannot export iron.
Is ferritin low or high in anaemia of inflammation?
Normal or high, because storage iron is plentiful and ferritin is an acute-phase protein.
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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Anemia of chronic disease: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.