Clinical Significance

    Ferritin is an iron-containing protein that functions as an iron storage compound, especially in hepatocytes and reticuloendothelial cells.  Each ferritin molecule can consist of 20% iron by weight when fully saturated.  About 25% of the iron in the body is present in various storage forms, 2/3 present as ferritin.
A low serum ferritin value is a good indicator of iron depletion.  Ferritin is useful to distinguish between iron deficient anemia (ferritin values decreased) and anemia of chronic disease (ferritin values normal or increased).  Ferritin is a good screening test to distinguish between microcytosis due to iron deficiency (ferritin value decreased) and microcytosis due to thalassemia (ferritin values normal or increased).  Elevated ferritin levels are seen in iron overload states, such as hereditary hemochromatosis, acute hepatitis, and Gaucher’s disease. Slightly elevated ferritin levels are seen in malignancy and chronic inflammatory diseases.