How do you interpret an iron panel?

Interpreting an Iron Panel

The most effective way to interpret an iron panel is to evaluate serum ferritin, transferrin saturation (TSAT), serum iron, and total iron binding capacity (TIBC) together to determine iron status, with serum ferritin being the single most useful marker for iron deficiency. 1

Key Components of an Iron Panel

Essential Parameters

• Serum Ferritin: Reflects iron stores

  • <15 μg/L: Definitive iron deficiency
  • <30 μg/L: Low body iron stores
  • <45 μg/L: Optimal cut-off for detecting iron deficiency 1
  • In inflammatory conditions: Consider higher cutoffs (up to 100 μg/L) 2

• Transferrin Saturation (TSAT): Ratio of serum iron to TIBC expressed as percentage

  • <20%: Suggests iron deficiency 2
  • <15%: Indicates iron-deficient erythropoiesis (Grade II iron deficiency) 3

• Serum Iron: Measures circulating iron

  • Normal range: 50-175 μg/dL 1
  • Decreases in iron deficiency
  • Highly variable with diurnal fluctuations

• Total Iron Binding Capacity (TIBC): Indirect measure of transferrin

  • Increases in iron deficiency
  • Helps calculate transferrin saturation

Supporting Parameters

• Complete Blood Count (CBC):

  • Hemoglobin (Hb): <13 g/dL in men or <12 g/dL in non-pregnant women suggests anemia 1
  • Mean Cell Volume (MCV): Low values (<80 fL) suggest microcytic anemia
  • Mean Cell Hemoglobin (MCH): More reliable marker than MCV for iron deficiency 1
  • Red Cell Distribution Width (RDW): >14% suggests iron deficiency 1

• Reticulocyte Hemoglobin Content (CHr): <30 pg suggests iron-restricted erythropoiesis 1

Interpretation Algorithm

1. Assess Iron Stores (Ferritin):

   • <15 μg/L: Severe depletion of iron stores
   • 15-30 μg/L: Depleted iron stores
   • 30-100 μg/L: With inflammation present, may still indicate iron deficiency

   • 100 μg/L: Adequate iron stores (unless severe inflammation present)

2. Evaluate Iron Transport (TSAT and TIBC):

   • TSAT <20% + increased TIBC: Classic iron deficiency
   • TSAT <20% + normal/low TIBC: Consider functional iron deficiency (inflammation)

3. Determine Iron Deficiency Stage 3:

   • Grade I (Iron Depletion): Decreased ferritin, normal TSAT (>15%)
   • Grade II (Iron-Deficient Erythropoiesis): Decreased ferritin, TSAT ≤15%
   • Grade III (Iron Deficiency Anemia): Grade II + low hemoglobin

4. Consider Confounding Factors:

   • Inflammation: Falsely elevates ferritin
   • Recent transfusion: Temporarily normalizes parameters
   • Liver disease: May elevate ferritin independent of iron status

Special Considerations

Inflammatory Conditions

When inflammation is present (elevated CRP, ESR, or acute illness):

• Ferritin acts as an acute phase reactant and may be falsely normal or elevated
• Use higher ferritin cutoffs (up to 100 μg/L) to diagnose iron deficiency 2
• Consider measuring soluble transferrin receptor (not affected by inflammation) 4

Therapeutic Response Assessment

A good response to iron therapy (Hb rise ≥10 g/L within 2 weeks) confirms iron deficiency even with equivocal iron studies 1

Common Pitfalls to Avoid

1. Relying on a single parameter: No single test is sufficient for diagnosis
2. Ignoring inflammation: Ferritin can be falsely normal in inflammatory states
3. Misinterpreting microcytosis: Consider thalassemia when MCV is low but iron studies are normal
4. Overlooking functional iron deficiency: Can occur despite normal ferritin levels, especially in chronic diseases

Clinical Applications

Iron Deficiency Without Anemia

• Ferritin <30 μg/L with normal hemoglobin
• May still cause symptoms like fatigue and reduced exercise capacity
• Requires investigation for underlying cause

Iron Deficiency Anemia

• Ferritin <30 μg/L with hemoglobin <13 g/dL (men) or <12 g/dL (women)
• Typically presents with microcytic, hypochromic anemia and elevated RDW
• Requires both iron replacement and investigation of underlying cause 5

Anemia of Chronic Disease/Inflammation

• Ferritin normal or elevated (>100 μg/L)
• TSAT <20%
• Normal or low TIBC
• Often normocytic, normochromic anemia

By systematically evaluating these parameters together, clinicians can accurately diagnose iron status and guide appropriate management decisions.