Total Iron Binding Capacity
Total Iron Binding Capacity (TIBC) measures your blood's total capacity to carry iron, which mostly reflects how much transferrin, the main iron-transport protein, is available. Think of it as the total number of 'seats' available for iron to bind.
TIBC works alongside serum iron and transferrin saturation to describe your iron status. Serum iron shows how many seats are filled, TIBC shows how many seats exist in total, and transferrin saturation is the percentage of seats occupied (serum iron divided by TIBC). Together these give a fuller picture than any single number.
A high TIBC often accompanies iron deficiency, because the body tends to make more transferrin when iron is scarce, creating more available binding capacity. It can also be influenced by pregnancy and certain other conditions. It's most meaningful when read next to serum iron and saturation.
A low TIBC can appear with iron overload, inflammation, chronic illness, or malnutrition. As with the other iron markers, the pattern across the whole panel matters more than the single value.
Reference ranges differ between labs, and TIBC is meant to be interpreted as part of the broader iron panel. A clinician can explain how your TIBC fits with your other results.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.