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. Transferrin saturation is a calculation representing the percentage of this transferrin that is saturated with iron.
In healthy people, approximately one-third of the transferrin is saturated with iron. This leaves two-thirds as a reserve for binding extra transferrin should it be required.
Transferrin saturation is calculated from the measured amounts of transferrin and iron in your blood. These tests are can be 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.
In known cases of iron deficiency, the amount of transferrin saturation is an extremely good indicator of the amount of iron depletion in the body. Transferrin saturation in particular, is used to check for chronic iron overload, for example with excessive intake or a genetic disease called hemochromatosis.
A high transferrin saturation results indicates you have too much iron in your body. In iron overload, the transferrin saturation is usually increased from around 30% to over 90%. Potential causes include excessive intake, possibly from iron supplements or multivitamins.
In some instances, it could also indicate genetic condition called hemochromatosis. This is an inherited disease in which the body absorbs too much iron, even on a normal diet. This disorder is most common in people from northern europe and is one of the more common genetic disorders.
Symptoms of iron overload include:
Treatments to reduce levels of iron are available, but the disease must be investigated and treated by a doctor.
Low transferrin saturation indicates you are likely to be suffering from iron deficiency. In iron deficiency, iron is low and fewer transferrin binding sites are used to the saturation of these binding sites is low.
Causes of iron deficiency can include:
Treatment for iron deficiency anaemia usually involves taking iron supplements and changing your diet as well as treating any underlying cause. Foods rich in iron include red meat, pork, poultry and seafood.
The body is less able to absorb the iron found in plant based foods such as spinach, lentils, beans, and so supplementation is often required for vegetarian and vegan diets.