Total iron-binding capacity (TIBC or transferrin) test
A total iron-binding capacity (TIBC or transferrin) test is used to measure the amount of iron in the body.
Transferrin is a glyco-protein that's found in blood plasma (the liquid part of blood). It's capable of binding iron and acts as a carrier for iron in the bloodstream.
If you have an iron deficiency (a lack of iron), your iron level will be low but your TIBC will be high.
If you have too much iron - for example, if you have a condition such as haemochromatosis, your iron level will be high but your TIBC will be low or normal.
As transferrin is produced by the liver, your TIBC level will also be low if you have liver disease.