What is the role of serum iron and ferritin testing in the diagnosis of iron deficiency anemia?

Updated: Aug 04, 2019
  • Author: James L Harper, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Low serum iron and ferritin levels with an elevated TIBC are diagnostic of iron deficiency. While a low serum ferritin is virtually diagnostic of iron deficiency, a normal serum ferritin can be seen in patients who are deficient in iron and have coexistent diseases (eg, hepatitis or anemia of chronic disorders). These test findings are useful in distinguishing iron deficiency anemia from other microcytic anemias (see the image below).

The sequence of events (left to right) that occur The sequence of events (left to right) that occur with gradual depletion of body stores of iron. Serum ferritin and stainable iron in tissue stores are the most sensitive laboratory indicators of mild iron deficiency and are particularly useful in differentiating iron deficiency from the anemia of chronic disorders. The percentage saturation of transferrin with iron and free erythrocyte protoporphyrin values do not become abnormal until tissue stores are depleted of iron. Subsequently, a decrease in the hemoglobin concentration occurs because iron is unavailable for heme synthesis. Red blood cell indices do not become abnormal for several months after tissue stores are depleted of iron.

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