Transferrin is a protein made by the liver. It is the main protein in the blood that binds to the iron absorbed from food and transports it throughout the body.
About 70% of the iron is transported to the bone marrow and used in the production of hemoglobin within red blood cells. The remainder is stored in tissues as ferritin. *You should fast for 12 hours before taking this test with only water is allowed.
Transferrin is measured to assess your body's ability to transport iron in the blood. It is usually measured with Iron and Ferritin to learn more about your body's iron stores if a doctor suspects you have too little or too much iron in your body.
Iron, transferrin and transferrin saturation blood tests are also used to check for chronic iron overload, for example with excessive intake or a genetic disease called hemochromatosis. Transferrin levels also drop when there is not enough protein in the diet, so this test can be used to monitor nutrition.
A high transferrin result indicates you may have iron deficiency. The liver will produce more transferrin to make use of all the iron available available in the body. *Transferrin can also be increased during pregnancy and with the use of oral contraceptives.
A low transferrin result may mean you are absorbing more iron than your body needs. The liver slows production of transferrin so less iron is in the blood and more is bound to ferritin and stored. This could be due to over supplementation with Iron tablets or multivitamins.
In rare cases a low transferrin can be caused by a genetic condition called hemochromatosis. This is an inherited disease in which the body absorbs too much iron, even on a normal diet.
Treatments to reduce levels of iron are available, but the disease must be investigated and treated by a doctor. Transferrin is made in the liver so transferrin will also be low if you are suffering from a liver disease or disorder.
*Transferrin levels are reduced in inflammation, for example if you are suffering from an infection and can be a common cause of a low transferrin result.