TIBC
What it measures, and what changes the number.
Total iron binding capacity (TIBC) measures how much iron the blood could carry if all the binding sites on transferrin, the main iron transport protein, were filled. It is essentially an indirect measure of transferrin.
It is part of the iron panel and is read with serum iron, from which transferrin saturation is calculated, and with ferritin and transferrin, which together describe iron stores and transport.
Some labs measure TIBC directly by saturating the sample with iron, while others calculate it from a transferrin measurement, and the two approaches do not always agree. Because it is usually drawn with serum iron, which varies through the day and after meals, iron panels are often collected in the morning after fasting. Reports may list it as IRON BINDING CAPACITY.
Often read alongside: Iron, Transferrin, Transferrin saturation, Ferritin