Anemia of Chronic Disease (Anemia of Inflammation)

Basics

Description

  • Anemia that accompanies a variety of systemic diseases, with the common features of chronicity and inflammation
  • Anemia of chronic disease is more properly called anemia of inflammation (AI) and is the combined result of mildly increased destruction of RBCs, relative erythropoietin resistance, and iron-restricted erythropoiesis.

Pathophysiology

Typically mild to moderate anemia (Hgb 7 to 12 g/dL); develops in the setting of infection, inflammatory disorders, and some malignancies

  • Deficient cellular iron in the setting of hepcidin excess (functionally inaccessible iron)
  • Typically normochromic, normocytic but, if long-standing, can be hypochromic, microcytic (especially in children)
  • Main mechanism appears to be
    • Hepcidin is increased by interleukin-6 (IL-6), causing depletion of ferroportin, the only known membrane iron transporter.
    • Elevated hepcidin results in macrophage inability to release iron recycled from senescent RBCs, hepatocyte inability to release stored iron, and enterocyte inability to absorb dietary iron.
    • These changes lead to iron restriction with decreased iron available for erythropoiesis.
  • Other factors contributing to anemia in various degrees include the following:
    • Increased red cell destruction
    • Diagnostic phlebotomy or other blood loss
    • Inflammatory cytokines suppress erythropoiesis
    • Cytokine-mediated suppression of erythropoiesis
    • Cytokines such as interleukin-1 (IL-1) and IL-6 can activate ferritin synthesis, leading to sequestration of iron, which eventually is converted into hemosiderin.

Etiology

Underlying disease process

Commonly Associated Conditions

  • Underlying disease process
    • Infections, both acute and chronic
    • Inflammatory disease
    • Collagen vascular diseases
    • Malignancies
    • Renal failure
  • Anemia of chronic disease often coexists with other causes of anemia, including:
    • Occult blood loss
    • Hemolysis
    • Dietary iron deficiency
    • Drug-related marrow suppression

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