Anemia of Chronic Disease with Functional Iron Deficiency
This patient has anemia of chronic disease (ACD) with functional iron deficiency, not true iron deficiency anemia, and requires investigation for an underlying inflammatory or chronic disease process rather than empiric iron supplementation or gastrointestinal workup.
Laboratory Interpretation
The lab pattern is diagnostic of functional iron deficiency in the context of inflammation:
- Hemoglobin 8.16 g/dL represents significant anemia requiring investigation 1
- Ferritin 236 μg/L is elevated and excludes absolute iron deficiency; ferritin >150 μg/L is unlikely to occur with true iron deficiency even with inflammation 1
- Normal MCHC (32.5) indicates normochromic anemia, not the hypochromic pattern typical of iron deficiency 1
- Transferrin saturation 34.7% (calculated: 66/190 × 100) is borderline low but not severely reduced 1
- Normal folate (32.9) excludes vitamin deficiency 1
This constellation—anemia with elevated ferritin, adequate iron stores, but impaired iron utilization—is pathognomonic for anemia of chronic disease with functional iron deficiency 1.
Recommended Diagnostic Approach
Immediate Workup Required
- Inflammatory markers: CRP, ESR to confirm inflammatory process 1
- Renal function: Creatinine and BUN, as chronic kidney disease commonly causes this pattern 1
- Complete blood count review: Evaluate other cell lines (WBC, platelets) for bone marrow dysfunction 1
- Reticulocyte count: Low/normal reticulocytes indicate inadequate bone marrow response; elevated suggests hemolysis 1
Secondary Investigations
- Thyroid function (TSH), as hypothyroidism causes normochromic normocytic anemia 1
- Vitamin B12 level if macrocytosis develops or other deficiencies suspected 1
- Hematology consultation if multiple cell lines abnormal or cause remains unclear 1
Critical Clinical Distinction
Gastrointestinal investigation is NOT indicated in this patient despite anemia. The British Society of Gastroenterology guidelines specify that ferritin >150 μg/L makes absolute iron deficiency "unlikely to occur" even with inflammation, and GI workup is reserved for true iron deficiency (ferritin <45 μg/L) 1. The elevated ferritin here points away from GI blood loss as the primary etiology 1.
Management Strategy
Do NOT Start Empiric Oral Iron
Oral iron supplementation is inappropriate because:
- Iron stores are adequate (ferritin 236) 1
- The problem is iron utilization, not availability 1
- Oral iron will not correct functional iron deficiency without treating the underlying condition 2, 3
Address the Underlying Cause
The priority is identifying and treating the chronic disease driving the anemia:
- Chronic kidney disease: Most common cause of this pattern; requires erythropoietin-stimulating agents if confirmed 1
- Chronic inflammation: IBD, rheumatologic disease, malignancy 1
- Infection: Chronic infections elevate ferritin as an acute-phase reactant 1
Consider Intravenous Iron Only After Diagnosis
If functional iron deficiency persists despite treating underlying disease, IV iron may bypass the reticuloendothelial blockade, but this decision requires knowing the primary diagnosis first 4, 2.
Common Pitfalls to Avoid
- Misinterpreting elevated ferritin as adequate iron status: Ferritin is an acute-phase reactant; elevation indicates inflammation, not necessarily usable iron 1
- Initiating GI workup based on anemia alone: The ferritin level excludes true iron deficiency requiring endoscopy 1
- Starting oral iron empirically: This will not address functional iron deficiency and delays proper diagnosis 2, 3
- Ignoring renal function: CKD is a leading cause of this exact laboratory pattern and requires specific management 1