Serum iron

What it measures

Measures iron bound to transferrin in the blood. It is interpreted together with TIBC, transferrin saturation and ferritin to assess iron deficiency or overload.

Specimen and preparation

• Specimen: Serum (non-hemolyzed)
• Tube: Gold top
• Preparation: Morning fasting sample preferred because levels vary through the day. Stop iron supplements for 24 h before testing.

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Hereditary hemochromatosis
• Repeated transfusions
• Iron supplements or iron poisoning
• Hemolytic and sideroblastic anemias
• Acute liver injury

Causes of low values

• Iron deficiency
• Anemia of chronic disease or inflammation
• Chronic blood loss
• Pregnancy (late)

Method

Colorimetric assay (ferrozine or similar) after release from transferrin

Good to know

A single serum iron value is unreliable on its own because of daily variation and recent meals. Hemolysis falsely raises the result.

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