Iron Studies

Iron studies are a panel consisting of most of:

• Ferritin
  Intracellular iron storage protein and the gold standard for assessing total iron stores. Ferritin is:
  • Synthesised in the liver at a rate proportional to serum iron
  • Found in all cells
    Plasma ferritin is proportionate to total body ferritin.
  • An acute phase reactant

Causes of Abnormal Ferritin Levels

↓ Ferritin	↑ Ferritin
Iron deficiency	Malignancy
	Iron overload: Haemochromotosis Transfusion-dependence
	Inflammation: HLH Still’s disease Juvenile idiopathic arthritis Rheumatological disease
	Infection: Sepsis HIV

• Serum Iron
  Total serum iron content, which:
  • Consists of both ferric (Fe³⁺) iron and transferrin-bound ferric iron
  • Undergoes substantial diurnal variation
  • ↓ With:
    • Iron deficiency
  • ↑ With:
    • Haemolysis
    • Iron toxicity
      • Overdose
      • Haemochromatosis
    • Hepatic necrosis
      
      
• Transferrin
  Iron binding protein that:
  • Delivers iron to the bone marrow
  • Binds free iron
    ↓ Availability to microbes.
  • Is a negative acute phase reactant
  • ↓ With:
    • Inflammation
    • Hepatic disease
    • Nephrotic syndrome
    • Malnutrition
  • ↑ With:
    • Iron deficiency
      
      
• Transferrin Saturation
  Proportion of transferrin binding sites filled with iron atoms.
  • ↓ With:
    • Iron deficiency
  • ↑ With:
    • Iron overload

Interpretation

Interpretation of Iron Studies

	Iron Deficiency Anaemia	Anaemia of Chronic Disease	Acute Phase Response	Iron Overload
MCV (80-100 fL)	↓	↓	Normal	Normal
MCHC (32-36 g/dL)	↓	↓	Normal	Normal
Ferritin (30-100 µg/L)	↓	Normal	↑	↑
Serum Iron (60-170 μg/dL)	↓	↓	↓	↑
Transferrin (Variable)	↑	↓	↓	Normal
Transferrin Saturation (20-50%)	↓	Normal	↓	↑
Total Iron Binding Capacity (240-450 μg/dL)	↑	↓/Normal	↓	↓
Response to Iron	Haemoglobin normalises	No response	No response	N/A
Notes			Partial response may occur with concurrent iron deficiency

Total iron binding capacity is calculated from transferrin.

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References