How do you interpret iron studies in a patient with severe anemia?

Interpretation of Iron Studies in Severe Anemia

The patient's iron studies indicate anemia of chronic disease with functional iron deficiency, requiring intravenous iron therapy to improve hemoglobin levels and replenish iron stores.

Analysis of Laboratory Values

The patient presents with severe anemia with the following values:

• Hemoglobin: 7.7 g/dL (severely low)
• Hematocrit: 25.6% (severely low)
• Transferrin: 183 mg/dL (low)
• Serum iron: 34 μg/dL (low)
• Ferritin: 385 ng/mL (elevated)
• Iron binding capacity: 256 mg/dL (low-normal)
• % Transferrin saturation: 13% (low)

Diagnostic Interpretation

This pattern represents a classic case of anemia of chronic disease with functional iron deficiency:

1. Low transferrin saturation (13%) - Below 20% indicates inadequate iron availability for erythropoiesis 1
2. Elevated ferritin (385 ng/mL) - Above normal range, suggesting inflammation rather than absolute iron deficiency 1
3. Low serum iron (34 μg/dL) - Indicates poor iron availability
4. Low transferrin (183 mg/dL) - Often decreased in chronic disease
5. Severe anemia (Hb 7.7 g/dL) - Requires prompt intervention

Differential Diagnosis

1. Anemia of chronic disease with functional iron deficiency - Most likely based on low transferrin saturation with elevated ferritin 1
2. Combined anemia of chronic disease and absolute iron deficiency - Possible but less likely given the elevated ferritin
3. Chronic kidney disease-associated anemia - Should be considered, especially with these iron parameters 1
4. Malignancy-associated anemia - Possible, particularly with elevated ferritin 1

Management Approach

Step 1: Evaluate for Underlying Cause

• Assess for chronic inflammatory conditions
• Check renal function (GFR, creatinine) 1
• Consider GI evaluation if blood loss suspected despite elevated ferritin 1

Step 2: Iron Replacement

• Intravenous iron therapy is indicated due to:

  • Severe anemia (Hb <10 g/dL)
  • Functional iron deficiency pattern (low TSAT, elevated ferritin)
  • Poor expected response to oral iron in this setting 1

• IV iron options include:

  • Iron sucrose: 200 mg IV weekly × 5 doses
  • Ferric carboxymaltose: 1000 mg IV as a single dose
  • Sodium ferric gluconate: 125 mg IV weekly × 8 doses 1

Step 3: Monitor Response

• Check hemoglobin after 2-4 weeks
• Expect hemoglobin rise of approximately 2 g/dL after 3-4 weeks of therapy 1
• If inadequate response, consider additional IV iron or erythropoiesis-stimulating agents 1

Important Considerations

• Do not rely on oral iron therapy in this scenario as it will likely be ineffective due to functional iron deficiency and hepcidin upregulation from inflammation 1
• Blood transfusion may be necessary if the patient is symptomatic (dyspnea, chest pain, significant fatigue) 1
• Continue iron therapy for at least 3 months after correction of anemia to replenish iron stores 1
• Investigate underlying causes of anemia thoroughly, as this pattern suggests a significant medical condition 1

Pitfalls to Avoid

• Do not misinterpret elevated ferritin as adequate iron stores - in inflammatory states, ferritin can be falsely elevated despite iron deficiency 1
• Do not rely solely on MCV for diagnosis - iron deficiency can be normocytic in the context of inflammation 1
• Do not delay IV iron therapy while pursuing diagnostic workup if the patient is symptomatic 1
• Do not stop iron therapy once hemoglobin normalizes - continue for 3 months to replenish stores 1

This pattern of iron studies requires prompt intervention with IV iron therapy while simultaneously investigating and treating the underlying cause of the anemia.