A 55-year-old woman presents to the clinic for a three-month history of worsening fatigue and generalized malaise. She has no recent changes in her bowel habits, no history of hematuria, and her menstrual cycles ceased five years ago. She has a 10-year history of rheumatoid arthritis, which is generally well-controlled with methotrexate. Physical examination reveals mild synovial thickening of the proximal interphalangeal joints, but no pallor or active bleeding.
Laboratory studies show the following:
Hemoglobin: 10.8 g/dL
Mean corpuscular volume (MCV): 86 fL
Platelet count: 260,000/μL
White blood cell count: 7,200/μL
Which of the following iron study profiles is most consistent with this patient's condition?
The correct answer is:
B) Decreased serum iron, decreased total iron-binding capacity, increased ferritin
This patient presents with anemia of chronic disease, also frequently termed anemia of inflammation. This condition is common in patients with chronic inflammatory states, such as rheumatoid arthritis, malignancy, or chronic infections. The pathophysiology is driven largely by hepcidin, an acute-phase reactant produced by the liver in response to inflammatory cytokines (particularly IL-6). Hepcidin inhibits ferroportin, the iron transporter responsible for releasing iron from macrophages and absorbing it from the gut. This leads to the sequestration of iron within macrophages and reduced iron availability for erythropoiesis. Serum iron is decreased due to sequestration. Total iron-binding capacity (TIBC) is decreased because the liver decreases the production of transferrin in response to inflammation. Ferritin is normal or increased because it reflects increased iron storage in macrophages and ferritin's role as an acute-phase reactant.
Answer choice A: Decreased serum iron, decreased total iron-binding capacity, decreased ferritin, is incorrect. This would represent a mixed picture or a very severe state.
Answer choice C: Decreased serum iron, increased total iron-binding capacity, decreased ferritin, is incorrect. This profile is the classic laboratory pattern of iron deficiency anemia (IDA).
Answer choice D: Increased serum iron, increased total iron-binding capacity, increased ferritin, is incorrect. This reflects iron overload as seen in hemochromatosis.
Answer choice E: Normal serum iron, normal total iron-binding capacity, normal ferritin, is incorrect. This patient clearly has anemia and a pathological process driving it, so would not have normal iron studies.
Key Learning Point
The hallmark of anemia of chronic disease is the discordance between low serum iron and low TIBC, combined with normal or high ferritin. Unlike iron deficiency anemia, where the body is starved of iron and makes more transferrin to scavenge what it can (increasing TIBC), in anemia of chronic disease, the body is actively hiding iron, and the liver downregulates transferrin production, thus decreasing TIBC.
