Background
Ferritin is a compound composed of iron molecules bound to apoferritin, a protein shell. Stored iron represents about 25% of total iron in the body, and most of this iron is stored as ferritin. Ferritin is found in many body cells, but especially those in the liver, spleen, bone marrow, and in reticuloendothelial cells.
Ferritin plays a significant role in the absorption, storage, and release of iron. As the storage form of iron, ferritin remains in the body tissues until it is needed for erythropoiesis. When needed, the iron molecules are released from the apoferritin shell and bind to transferrin, the circulating plasma protein that transports iron to the erythropoietic cells.
Although dietary iron is poorly absorbed, the body conserves its iron stores carefully, reabsorbing most of the iron released from the breakdown of red blood cells. As a result, the body normally loses only 1 to 2 mg of iron per day, which is generally restored by the iron absorbed in the small intestine from dietary sources.
Ferritin is found in serum in low concentrations and is directly proportional to the body’s iron stores. Serum ferritin concentration, when analyzed with other factors such as serum iron, iron binding capacity, and tissue iron stores, is valuable in the diagnosis of iron-deficiency anemias’s, anemia’s of chronic infection, and conditions such as thalassemia and hemochromatosis that are associated with iron overload. Measurement of serum ferritin is particularly valuable in distinguishing iron-deficiency anemia caused by low iron stores from those resulting from inadequate iron utilization.
Serum ferritin values are elevated in the presence of the following conditions and do not reflect actual body iron stores:
- inflammation
- significant tissue destruction
- liver disease
- malignancies such as acute leukaemia and Hodgkin’s disease
- therapy with iron supplements
Reference ranges
FERRITIN guide to interpretation:
Low: Less than 15 ug/L
Borderline: 16 – 40 ug/L
Normal: 41 – 400 ug/L
High: Greater than 400
Specimen requirements
Serum
Turnaround time
6 hours