How are UIBC and TIBC measured?

Transferrin is the protein that carries iron in your blood. Unsaturated iron binding capacity (UIBC) measures how much more iron your transferrin could carry, while total iron-binding capacity (TIBC) shows its total iron-carrying capacity.

The laboratory measures UIBC directly. TIBC is then calculated by adding your UIBC result to your serum iron level. Together, these measurements help assess your iron status.