Iron studies

Iron studies

Introduction

Iron studies are a group of blood tests used to evaluate iron metabolism and storage in the body. They are crucial in distinguishing between different types of anaemia and in diagnosing iron overload conditions such as haemochromatosis.

Components of Iron Studies

  • Serum Iron
    • Measures the concentration of circulating iron bound to transferrin.
    • Increased in:
      • Haemochromatosis
      • Repeated blood transfusions
      • Ineffective erythropoiesis (e.g. thalassaemia, sideroblastic anaemia)
      • Iron poisoning
    • Decreased in:
      • Iron deficiency (e.g. blood loss, poor intake)
      • Anaemia of chronic disease
      • Pregnancy
      • Malnutrition
  • Total Iron Binding Capacity (TIBC)
    • Indicates the maximum amount of iron that transferrin can carry.
    • Inversely related to iron stores — it increases when iron is low.
  • Transferrin Saturation
    • Calculated as: (Serum Iron ÷ TIBC) × 100
    • Reflects the percentage of transferrin that is saturated with iron.
    • Decreased in iron deficiency; increased in iron overload.
  • Ferritin
    • Reflects stored iron in tissues.
    • Also acts as an acute-phase reactant, increasing in inflammation.
    • Increased in:
      • Iron overload
      • Acute and chronic inflammation
      • Sideroblastic anaemia
    • Decreased in:
      • Iron deficiency (earliest and most sensitive marker)

Key Patterns in Common Conditions

  • Iron Deficiency Anaemia
    • ↓ Serum iron
    • ↓ Ferritin
    • ↑ TIBC
    • ↓ Transferrin saturation
    • Common causes: chronic blood loss (e.g. GI bleeding), poor dietary intake, pregnancy, malabsorption (e.g. coeliac disease)
  • Iron Overload (e.g. Haemochromatosis)
    • ↑ Serum iron
    • ↑ Ferritin
    • ↓ TIBC
    • ↑ Transferrin saturation
    • Common causes: hereditary haemochromatosis, repeated transfusions, ineffective erythropoiesis
  • Anaemia of Chronic Disease (Inflammation)
    • ↓ Serum iron
    • Normal or ↑ Ferritin
    • ↓ TIBC
    • ↓ Transferrin saturation
    • Seen in: chronic infections, autoimmune conditions, malignancy

FAQ from our users

Why is ferritin elevated in inflammation if iron levels are low?
  • Ferritin is an acute phase reactant – it increases in response to inflammation regardless of iron status.

Common pitfalls in a clinical setting

Common pitfalls in a clinical setting
Common pitfalls in a clinical setting
  • TIBC and transferrin saturation can help differentiate between iron deficiency anemia and anemia of chronic disease.
  • Ferritin is the best diagnostic tool for diagnosing iron deficiency and is also a useful marker for iron overload.
    • but its levels can be increased in the presence of inflammation (acute phase reaction).
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