Ferritin is a protein which can store about 4500 iron ions in a hollow shell made of 24 identical subunits. Inside the ferritin shell, iron ions form crystallites together with phosphate and hydroxide ions.
Uses
Serum ferritin levels are measured in patients as part of the iron studies workup for anemia. The ferritin levels measured have a direct correlation with the total amount of iron stored in the body.
Ferritin is also used as a marker for iron overload disorders, such as haemochromatosis in which the ferritin level may be abnormally raised.
As ferritin is also an acute phase reactant, it is often elevated in the course of disease. A normal C-reactive protein can be used to exclude elevated ferritin caused by acute phase reactions.