Transferrin
Transferrin is the plasma protein that carries iron from absorption sites and storage to the bone marrow. Direct measure of what TIBC estimates indirectly.
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What it measures
Transferrin is the glycoprotein synthesized in the liver that binds and transports iron through circulation. Each molecule can carry up to two iron atoms; in steady-state physiology about 30% of transferrin is iron-saturated. Direct transferrin measurement gives the same clinical information as TIBC (which is calculated FROM transferrin) and is preferred in some labs because it is more reproducible.
What a high value can mean
- Iron-deficiency anaemia — body upregulates transferrin synthesis.
- Pregnancy, oral contraceptives — estrogen-driven rise.
What a low value can mean
- Anaemia of chronic disease — hepcidin downregulates.
- Iron overload / hemochromatosis — synthesis falls when stores are saturated.
- Protein-loss states — nephrotic syndrome, malnutrition, severe burns, advanced liver disease.
- Active inflammation, malignancy.
When to discuss with a doctor
Direct transferrin and TIBC tell the same story; if your lab reports one, the other is implied. Interpretation is always alongside serum iron and ferritin. Mediora.AI shows the full iron panel together.