Hematology · Anemia
The facts most likely to be tested
Anemia of chronic disease is driven by hepcidin-mediated sequestration of iron within macrophages, preventing its release into the plasma.
Laboratory findings typically show low serum iron, low total iron-binding capacity (TIBC), and normal or elevated ferritin levels.
The anemia is classically normocytic or mildly microcytic in morphology with a low reticulocyte count.
Chronic inflammatory states increase cytokines like IL-6, which directly stimulate the hepatic production of hepcidin.
The primary diagnostic distinction from iron deficiency anemia is the elevated ferritin and low TIBC seen in chronic disease.
Bone marrow examination, if performed, would reveal abundant iron stores within macrophages despite the low serum iron levels.
The most effective management strategy is to treat the underlying inflammatory, infectious, or malignant condition rather than administering iron supplementation.
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A 62-year-old male with a 10-year history of rheumatoid arthritis presents for a routine follow-up. He reports generalized fatigue and decreased exercise tolerance. Laboratory studies reveal a hemoglobin of 10.2 g/dL, MCV of 84 fL, low serum iron, low TIBC, and an elevated ferritin of 350 ng/mL. His peripheral smear shows normocytic, normochromic red blood cells with no evidence of hemolysis.
What is the most likely mechanism underlying this patient's anemia?
Hepcidin-mediated iron sequestration
The patient's profile of low iron, low TIBC, and high ferritin in the setting of chronic inflammation is diagnostic of anemia of chronic disease, which is caused by hepcidin-induced iron trapping.
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Etiology / Epidemiology
Occurs in chronic inflammation, infection, or malignancy. Driven by hepcidin-mediated iron sequestration.
Clinical Manifestations
Usually asymptomatic or mild fatigue. Look for underlying chronic disease state.
Diagnosis
Diagnosis of exclusion. Low serum iron, low TIBC, and high ferritin.
Treatment
Treat the underlying condition. Use erythropoietin only if symptomatic and renal failure is present.
Prognosis
Prognosis depends on the primary disease. Anemia is rarely the primary cause of mortality.
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Epidemiology & Etiology
Common in patients with rheumatoid arthritis, chronic kidney disease, or solid tumors. It is the most common anemia in hospitalized patients. Often presents as a normocytic, normochromic anemia.
Pertinent Anatomy
The liver produces hepcidin, the master regulator of iron homeostasis. The bone marrow is the site of erythropoiesis, which becomes suppressed by inflammatory cytokines.
Pathophysiology
Inflammatory cytokines (IL-6) increase hepcidin levels, which blocks iron release from macrophages and intestinal absorption. This creates a functional iron deficiency despite adequate iron stores. Erythropoietin production is also blunted, and marrow response to erythropoietin is reduced.
Clinical Manifestations
Patients typically present with symptoms of the underlying chronic inflammatory state. Red flags include unexplained weight loss or night sweats suggesting malignancy. Physical exam is often unremarkable, lacking the koilonychia or glossitis seen in iron deficiency.
Diagnosis
The gold standard is a complete iron panel. Expect low serum iron, low TIBC, and high ferritin (>100 ng/mL). A bone marrow biopsy (rarely needed) would show abundant iron in macrophages.
Treatment
The first-line approach is treating the underlying inflammatory or malignant process. Iron supplementation is generally ineffective and contraindicated if ferritin is high. Erythropoietin-stimulating agents are reserved for patients with symptomatic anemia and renal failure.
Prognosis
The anemia is typically mild (Hgb 8-10 g/dL) and stable. Key complications involve the progression of the primary disease. Monitor Hgb levels periodically to ensure no secondary causes develop.
Differential Diagnosis
Iron Deficiency Anemia: High TIBC and low ferritin
Thalassemia: Normal iron studies with abnormal hemoglobin electrophoresis
Sideroblastic Anemia: High serum iron and high ferritin with ringed sideroblasts
Aplastic Anemia: Pancytopenia on CBC
Myelodysplastic Syndrome: Dysplastic cells on peripheral smear