Chapter 13: Anemia of Chronic Inflammation

DEFINITION

• Anemia associated with chronic infection, inflammatory or neoplastic disease.

• Also referred to as anemia of chronic disease.

• One to 2 months of sustained disease is required for anemia to develop.

• Anemia is moderate, with a hemoglobin level between 7 and 11 g/dL, and is rarely symptomatic.

• The characteristic features of anemia of inflammation (AI) are listed in Table 13–1.

PATHOGENESIS

• Inflammation leads to interleukin (IL)-6 production, which induces hepatocyte hepcidin production, which blocks intestinal iron absorption and iron release from macrophages and hepatocytes. Hepcidin binds to and leads to feroportin degradation, the primary cell surface iron exporter.

• Impaired intestinal iron uptake and impaired release of iron from macrophages leads to a low level of serum iron and consequent low saturation of transferrin.

• Enhanced activity of macrophages increases erythrocyte destruction.

• Production of erythropoietin (EPO) is decreased in response to anemia, and the ability of erythroid precursors to respond to EPO is impaired, both also related to inflammatory cytokine production (IL-1, tumor necrosis factor, interferons).

CLINICAL AND LABORATORY FEATURES

• Anemia is usually overshadowed by symptoms of the primary disease.

• Common conditions leading to AI are shown in Table 13–2.

• Low reticulocyte index for the degree of anemia.

• Diagnosis, especially differentiation from iron-deficiency anemia (IDA), depends on laboratory findings (see Table 13–1):

  — Initially normochromic, normocytic anemia; hypochromic, microcytic features develop as anemia progresses.

  — Low serum iron level and somewhat decreased serum transferrin concentration; decreased percent saturation of transferrin.

  — Level of serum ferritin, an acute phase protein, is inappropriately elevated (approximately threefold) with respect to storage iron.

  — Marrow contains increased storage iron. The M/E ...