Ferritin

Ferritin (serum ferritin; indicator of iron stores) is used to assess whole‑body iron stores and to differentiate iron deficiency anemia from other causes of anemia, including anemia of chronic disease. The test supports evaluation for iron overload, such as hereditary hemochromatosis, in which ferritin and iron saturation are increased. It is also used to track response to therapy in iron deficiency and in conditions associated with iron overload. Because ferritin reflects stored iron, incorporating it with other iron studies enhances diagnostic accuracy. Synonyms such as stored iron and metalloprotein may appear in clinical documentation and refer to the same measurement.

Ferritin is the primary intracellular protein for iron storage and is abundant in the liver, bone marrow, spleen, and muscle. Circulating ferritin correlates with iron stores and typically falls early in iron deficiency, often preceding the onset of anemia. Excess iron intake or absorption leads to tissue accumulation and can injure the liver, heart, and pancreas. Ferritin also behaves as an acute‑phase reactant and may be elevated with inflammation, chronic infection, autoimmune disease, liver disease, or malignancy; levels may decline in late pregnancy. Interpretation is strengthened by reviewing complementary iron studies, including serum iron, total iron‑binding capacity, transferrin, and transferrin saturation.