Ferritin has a central role in iron homeostasis since it binds and sequesters intracellular iron. It is a spheric shell with a central cavity where up to 4,500 atoms of iron are oxidized and stored. Ferritin is a multimer composed of 24 H (heavy) and L (light) subunits in variable proportions in different tissues. The two subunits are highly conserved during evolution, but only the H subunit has ferroxidase activity.1 Ferritin is also released in the circulation prevalently as L-ferritin or G-(glycosylated)-subunit through a largely unknown process. Since over recent years serum ferritin measurement has become a routine laboratory test, elevated serum ferritin is a common finding in clinical practice. High serum ferritin is found in a large spectrum of conditions both genetic and acquired, associated or not with iron overload. For this reason a precise diagnosis of hyperferritinemia requires a strategy that includes family and personal medical history, biochemical and eventually genetic or other tests, especially those related to tissue iron measurement.
