Transferrin is a transport protein that is produced in the liver and is responsible for the transport of iron in blood plasma. It also binds trace elements such as chromium, copper, manganese and zinc with a lower affinity.
Transferrin saturation is calculated from the concentration of iron and transferrin in serum (transferrin saturation (%) = serum iron (ug/dl): serum transferrin (mg/dl) x 70.9). A normal transferrin saturation largely rules out hemochromatosis, for example. A diagnostic isolated determination of transferrin is pointless because transferrin only reacts when the iron reserves of the body are completely depleted. Diagnostically, it can only be evaluated together with the iron level (most likely in the form of transferrin saturation) and ferritin.