What is the serum iron level in iron deficiency anemia?

• A. Decreased
• B. Increased
• C. Normal
• D. Variable

Answer: (A)

Serum iron reflects the amount of iron circulating in the blood bound to transferrin. In iron deficiency anemia, the body's iron stores are depleted and it cannot mobilize iron effectively into the bloodstream, so the circulating iron level falls. This is why the serum iron is decreased. The body compensates by increasing transferrin production, which raises the total iron-binding capacity, and transferrin saturation drops as a result. While there can be variation early on or in mixed cases, the classic finding in established iron deficiency is a decreased serum iron.