Anemia of chronic disease

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Pathophysiology - Chronic Inflammation's Iron Fist

  • Central Mediator: Chronic inflammation (autoimmune, infectious, malignant) ↑ key cytokines like IL-6.
  • Hepcidin Surge: IL-6 triggers the liver to release hepcidin, the master iron regulator.
  • Iron Sequestration: Hepcidin acts as an "iron gatekeeper":
    • Blocks ferroportin channels in the gut, ↓ dietary iron absorption.
    • Traps iron within macrophages of the reticuloendothelial system (RES).
  • Result: Functional iron deficiency. Despite adequate body stores (↑ ferritin), iron is unavailable for erythropoiesis, leading to ↓ heme synthesis.
  • Other Factors: Blunted erythropoietin (EPO) response.

Hepcidin and ferroportin in iron regulation and anemia

⭐ Despite low serum iron, ferritin levels are paradoxically normal or ↑ because it's an acute phase reactant and reflects trapped iron stores. This is a key diagnostic clue.

Diagnosis & Labs - Cracking the Code

  • CBC/Blood Smear: Initially normocytic, normochromic anemia (MCV 80-100 fL); can become microcytic over time.
  • Iron Studies Panel: The key to diagnosis.
    • ↓ Serum Iron
    • ↓ Total Iron-Binding Capacity (TIBC)
    • ↑ or Normal Serum Ferritin (acute phase reactant)
    • ↓ Transferrin Saturation (<20%)
  • Advanced Markers:
    • ↑ Hepcidin (confirms pathophysiology)
    • Normal soluble transferrin receptor (sTfR)

⭐ Serum ferritin, an acute-phase reactant, is characteristically normal or elevated in ACD, contrasting sharply with its depletion in pure iron deficiency anemia.

Differential Diagnosis - Anemia Imposters

  • Iron Deficiency Anemia (IDA): The most critical differential. Overlaps with early ACD (normocytic).
  • Thalassemia: Presents with microcytic anemia but with normal or ↑ iron stores.
  • Sideroblastic Anemia: Can be microcytic; characterized by ring sideroblasts in bone marrow.

⭐ The soluble transferrin receptor (sTfR) level is normal in ACD but elevated in IDA. The sTfR/log(ferritin) index is highly specific for differentiating IDA from ACD.

Management - Treating the Cause

  • Primary Goal: Resolve the underlying chronic disease (e.g., infection, autoimmune condition, malignancy).
  • Iron Supplementation: Only if coexistent iron deficiency is confirmed (↓ ferritin). IV iron is often preferred due to poor oral absorption from hepcidin block.
  • Erythropoiesis-Stimulating Agents (ESAs): Consider for specific conditions like CKD or myelosuppressive chemotherapy if anemia is symptomatic.

⭐ ESAs (e.g., epoetin alfa) require adequate iron stores to be effective and may increase the risk of thrombosis and hypertension.

High-Yield Points - ⚡ Biggest Takeaways

  • ACD is a normocytic, normochromic anemia, but can become microcytic over time.
  • It is driven by inflammatory cytokines (e.g., IL-6) in chronic diseases, which stimulate ↑ hepcidin production.
  • Hepcidin blocks iron release from macrophages and reduces gut absorption, leading to functional iron deficiency.
  • Key lab profile: ↓ serum iron, ↓ TIBC, and normal or ↑ ferritin (an acute-phase reactant).
  • Bone marrow shows adequate iron stores, unlike in true iron deficiency.
  • Management focuses on treating the underlying condition.

Practice Questions: Anemia of chronic disease

Test your understanding with these related questions

A 78-year-old man presents with fatigue and exertional dyspnea. The patient says that symptoms onset gradually 4 weeks ago and have not improved. He denies any history of anemia or nutritional deficiency. Past medical history is significant for ST-elevation myocardial infarction 6 months ago, status post coronary artery bypass graft, complicated by recurrent hemodynamically unstable ventricular tachycardia. Current medications are rosuvastatin, aspirin, and amiodarone. His blood pressure is 100/70 mm Hg, the pulse is 71/min, the temperature is 36.5°C (97.7°F), and the respiratory rate is 16/min. On physical examination, patient appears lethargic and tired. Skin is dry and coarse, and there is generalized pitting edema present. A complete blood count (CBC) and a peripheral blood smear show evidence of normochromic, normocytic anemia. Additional laboratory tests reveal decreased serum level of iron, decreased TIBC (total iron-binding capacity) and increased serum level of ferritin. Which of the following is the most likely etiology of the anemia in this patient?

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Flashcards: Anemia of chronic disease

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Treatment of aplastic anemia includes _____, such as EPO, GM-CSF, and G-CSF

TAP TO REVEAL ANSWER

Treatment of aplastic anemia includes _____, such as EPO, GM-CSF, and G-CSF

marrow-stimulating factors

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