Transferrin capacity — elevated in iron deficiency, suppressed in iron overload.
TIBC measures transferrin's total binding capacity for iron. In iron deficiency, TIBC rises (more "empty seats" on the carrier) even before ferritin fully depletes. In iron overload (hemochromatosis), TIBC is suppressed.
Transferrin saturation (serum iron ÷ TIBC × 100) is the functional derived metric — optimal range is typically 25–45%.
TIBC is influenced by: iron status (rises in deficiency, falls in overload), protein synthesis (low in liver disease or malnutrition), estrogen (raises it), and inflammation (suppresses it).
Reviewed as part of a full iron panel every 6–12 months when tracking iron. Persistent high saturation (>50%) warrants HFE gene workup for hemochromatosis.
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Start tracking →Informational only — not medical advice. Reference ranges vary by lab and individual context. Work with a licensed provider to interpret your specific results.