Total Iron-Binding Capacity (TIBC)
TIBC measures how much iron the blood could theoretically carry. Together with serum iron and ferritin it pins down iron-deficiency vs anaemia of chronic disease vs iron overload.
What it measures
TIBC is a measurement of the total amount of iron that transferrin (the iron-transport protein) could bind if every transferrin molecule were saturated. It's essentially a proxy for the transferrin concentration. The body upregulates transferrin production when iron stores are low, raising TIBC — so high TIBC is a classic finding in iron-deficiency anaemia. Conversely, in chronic inflammation, malnutrition or iron overload, transferrin synthesis drops and TIBC falls. Used with serum iron to calculate transferrin saturation (TSAT = iron / TIBC × 100).
What a high value can mean
- Iron-deficiency anaemia — the textbook finding; body upregulates transferrin to scavenge any remaining iron.
- Late pregnancy — physiological rise.
- Oral contraceptives, estrogen therapy — pharmacological rise.
What a low value can mean
- Anaemia of chronic disease — hepcidin downregulates transferrin synthesis; TIBC and iron both fall.
- Hemochromatosis or iron overload — body stops making transferrin when stores are full.
- Malnutrition, chronic liver disease, nephrotic syndrome — protein-loss states; transferrin is a negative acute-phase reactant.
- Active inflammation, malignancy — similar mechanism to anaemia of chronic disease.
When to discuss with a doctor
TIBC is rarely interpreted alone — it is the denominator in the transferrin-saturation calculation. Together with serum iron and ferritin it lets a clinician place the patient into one of three iron-physiology buckets (deficiency / chronic-disease / overload). Mediora.AI shows the full panel; treatment depends on which bucket.