What is serum ferritin?

By William Aird

A very small fraction of total ferritin circulates in blood. In contrast to its cellular counterpart, serum ferritin does not contain any iron and is almost entirely made up of L chains. It does not play a role in iron transport or cellular iron uptake. Indeed, its function is unknown. Serum ferritin is widely used as a convenient surrogate measure of body iron stores.