Transferrin (also known as siderophilin) is a glycoprotein synthesized in the liver. Transferrin is the main protein in the blood that binds to iron and transports it throughout the body. The main role of transferrin is to deliver iron from absorption centres in the duodenum and red blood cell macrophages to all tissues. It also plays a key role where erythropoiesis and active cell division occur. This test is usually performed to determine the cause of anemia, to examine iron metabolism (for example, in iron deficiency anemia), to determine the iron-carrying capacity of the blood, and can also be used to monitor nutrition. Serum transferrin levels DECREASE in inflammation, liver disease, iron overload and if protein is leaking into the urine or the digestive tract HIGH transferrin levels are seen in iron deficiency and primary or secondary liver cancer, and also in response to estrogenemia and certain drugs (especially diuretics).