Transferrin: A plasmaprotein that transports iron through the blood to the liver, spleen and bone marrow.
The blood transferrin level is tested for diverse reasons: to determine the cause of anemia, to examine iron metabolism (for example, in irondeficiencyanemia) and to determine the iron-carrying capacity of the blood.
When a transferrinprotein loaded with iron encounters a transferrin receptor on the surface of a cell, it binds to it and is consequently transported into the cell in a vesicle.