What is included in iron studies lab work?

Iron Studies Lab Work Components

Iron studies lab work typically includes serum ferritin, serum iron, total iron-binding capacity (TIBC), transferrin saturation, and complete blood count with hemoglobin. 1, 2

Core Components of Iron Studies

Primary Measurements

• Serum Ferritin

  • Measures iron storage in the body
  • Reference ranges: 20-250 μg/L in men, 20-200 μg/L in women 1
  • Most sensitive early indicator of iron deficiency
  • Low ferritin (<30 ng/mL) is diagnostic of iron deficiency in non-inflammatory conditions 3

• Serum Iron

  • Measures circulating iron in blood
  • Reference range: 50-175 μg/dL 1
  • Subject to diurnal variation (higher in morning, lower at night) 1
  • Can be affected by recent meals and inflammation 1

• Total Iron-Binding Capacity (TIBC)

  • Measures the blood's capacity to bind iron with transferrin
  • Reference range: 250-370 μg/dL 1
  • Increases when iron stores are low 1

• Transferrin Saturation

  • Calculated as: (Serum iron concentration ÷ TIBC) × 100
  • Expressed as a percentage
  • Reference range: 20-50% 1
  • Values <16% often used to confirm iron deficiency 1

Additional Components

• Complete Blood Count (CBC)

  • Includes hemoglobin, hematocrit, and red cell indices
  • Mean Cell Volume (MCV): 80-100 fL 1
  • Low MCV indicates microcytosis, common in iron deficiency 2

• Newer Methods (less commonly available)

  • Hepcidin: Promising for diagnosing deficiency in inflammatory conditions 1
  • Reticulocyte hemoglobin content: Reflects iron available for erythropoiesis 1
  • Soluble transferrin receptor: Less affected by inflammation than ferritin 1

Clinical Interpretation

Diagnosing Iron Deficiency

• Serum ferritin <30 ng/mL is diagnostic in non-inflammatory conditions 3
• In inflammatory states, use higher cutoff values (up to 100 μg/L) 2
• Transferrin saturation <20% suggests iron deficiency 1

Special Considerations

• Ferritin is an acute-phase reactant and may be falsely elevated in:

  • Chronic infection
  • Inflammation
  • Liver disease
  • Malignancy 1

• When results are unclear, bone marrow iron staining remains the gold standard for diagnosis 1

Pitfalls to Avoid

• Relying solely on serum iron, which has significant diurnal and day-to-day variation 1
• Failing to consider inflammatory conditions when interpreting ferritin levels 2
• Not accounting for recent meals when measuring serum iron (increases after meals) 1
• Using inappropriate cutoffs for different populations (e.g., pregnant women, children) 2

Iron studies should be interpreted together rather than as individual tests to get a complete picture of iron status, as each component has limitations when used alone.