Hematology Oncology · Year 2 · from Hematology Oncology

Case 3: Combined Iron Deficiency and Anemia of Chronic Disease

Patient Presentation

Demographics: 62-year-old female

Chief Complaint: Progressive fatigue and weakness over 6 weeks

History of Present Illness: The patient has a history of Crohn's disease involving the terminal ileum, currently on vedolizumab. She reports increasing fatigue and has noticed darker stools over the past month. She has had two disease flares requiring hospitalization in the past year.

Physical Examination:

  • Vital signs: BP 100/62, HR 102, RR 18, Temp 37.2C
  • General: Pale, fatigued-appearing
  • HEENT: Conjunctival pallor, angular cheilitis
  • Cardiac: Tachycardic, II/VI systolic ejection murmur
  • Abdomen: Mild right lower quadrant tenderness, no masses

Workup and Results

Complete Blood Count:

  • Hemoglobin: 8.0 g/dL
  • MCV: 76 fL (low)
  • RDW: 17% (elevated)
  • Platelets: 450,000/uL

Iron Studies:

  • Serum iron: 30 mcg/dL (low)
  • TIBC: 280 mcg/dL (normal)
  • Transferrin saturation: 11% (low)
  • Ferritin: 55 ng/mL (intermediate - neither clearly low nor elevated)

Additional Studies:

  • Soluble transferrin receptor: 4.2 mg/L (elevated, normal < 2.5)
  • sTfR/log ferritin ratio: 2.4 (> 2 suggests iron deficiency)
  • CRP: 18 mg/L (elevated)

Diagnosis

Combined Iron Deficiency Anemia and Anemia of Chronic Disease

The intermediate ferritin (30-100 ng/mL range) in setting of inflammation creates diagnostic uncertainty. The elevated soluble transferrin receptor and sTfR/log ferritin ratio > 2 confirm superimposed true iron deficiency.

Treatment Plan

  1. Address both problems:
  • IV iron (ferric carboxymaltose or iron sucrose) - preferred over oral due to:
  • Terminal ileum disease causing malabsorption
  • Ongoing inflammation blocking oral absorption
  • Optimize Crohn's disease management
  1. GI evaluation:
  • Colonoscopy to evaluate disease activity and exclude other bleeding sources
  1. Monitoring:
  • Check hemoglobin in 2-4 weeks after IV iron
  • Repeat ferritin 8-12 weeks after infusion

Teaching Points

  1. Combined iron deficiency and ACD commonly coexist, especially in inflammatory bowel disease
  2. Ferritin between 30-100 ng/mL in inflammatory states is diagnostically challenging
  3. Soluble transferrin receptor (sTfR) is elevated in iron deficiency but normal in ACD
  4. The sTfR/log ferritin ratio > 2 suggests true iron deficiency even in inflammation
  5. IV iron is preferred when oral absorption is compromised (malabsorption, active inflammation)
  6. Both the underlying inflammation AND the iron deficiency must be addressed

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