Serum Iron

Overview

Serum iron measures the concentration of circulating iron bound to transferrin in blood, reflecting the amount of iron available for hemoglobin synthesis and other metabolic functions. Iron is essential for oxygen transport via hemoglobin and myoglobin, energy production, and DNA synthesis. Low levels indicate iron deficiency from blood loss, poor absorption, or increased demand, while high levels suggest iron overload conditions like hemochromatosis or multiple transfusions; it is clinically useful for diagnosing iron deficiency anemia, monitoring iron supplementation, and evaluating iron storage disorders when combined with iron studies.

Clinical Use Cases

  • Diagnosing iron deficiency anemia.
  • Monitoring response to iron supplementation or parenteral iron therapy.
  • Evaluating hereditary hemochromatosis or secondary iron overload.
  • Assessing anemia of chronic disease differentiation.
  • Preoperative optimization in high-risk surgical patients.

Specimen Types

  • Serum (preferred).
  • Plasma (heparin or EDTA).

Measurement Methods

  • Colorimetric ferrozine-based assay.
  • Automated clinical chemistry analyzers.
  • Atomic absorption spectroscopy (reference method).

Test Preparation and Influencing Factors

  • Fasting 8-12 hours required (morning collection preferred).
  • Avoid vitamin C or iron supplements 24 hours prior.
  • Diurnal variation: levels highest in morning, lowest evening.
  • Recent iron ingestion, intramuscular iron, or hemolysis falsely elevates.
  • Inflammation or infection decreases levels as acute phase response.

Synonyms

  • Plasma iron.
  • Fe.

Further Reading

  • “Serum Iron Test” – MedlinePlus, NIH –