Transferrin
Iron transport protein for assessing iron metabolism capacity
Also known as
Definition
Transferrin is the primary iron transport protein in the blood and is synthesized mainly in the liver. It transports ferric iron (Fe³⁺) from sites of absorption (intestine, macrophages) to consuming tissues (bone marrow, liver). With iron deficiency, transferrin rises (compensatory); with iron overload or inflammation, it falls. Together with ferritin and transferrin saturation, it forms the diagnostic triad for iron metabolism disorders.
| Parameter | Value |
|---|---|
| Unit | g/l |
| Reference Range | 2.0–3.6 g/l |
| Optimal Range (lab2go) | 2.2–3.2 g/l (lab2go Optimum Zone — lower range with iron overload, upper range with iron deficiency; balanced around 2.5–3.0 g/l) |
↓ What a low value means
Low transferrin (< 2.0 g/l) can indicate chronic inflammation (acute phase reaction lowers transferrin), liver damage (reduced synthesis), protein deficiency/malnutrition, or iron overload (hemochromatosis). Transferrin is a negative acute-phase marker: falls with inflammation, rises during recovery.
↑ What a high value means
Elevated transferrin (> 3.6 g/l) is typical of iron deficiency (compensatory upregulation) or pregnancy. High transferrin combined with low ferritin and low transferrin saturation confirms iron deficiency. Rarely: congenital atransferrinemia (no transferrin production).
✓ How to optimize this marker
Transferrin itself cannot be directly supplemented; normalize by addressing the underlying cause: iron supplementation for iron deficiency, treat the underlying condition for chronic inflammation, ensure adequate protein intake (transferrin is a protein). Follow-up tests show response.
When to test
Always together with ferritin and serum iron to calculate transferrin saturation. For anemia workup, iron deficiency screening, hemochromatosis evaluation, chronic inflammation, or liver disease. Not useful as a standalone marker.
Frequently asked questions
Why does transferrin rise with iron deficiency? +
With iron deficiency, fewer iron-transferrin receptor complexes are internalized — as compensation, the body increases transferrin synthesis in the liver to bind and transport more iron molecules. This inverse relationship between iron status and transferrin makes transferrin an iron deficiency marker.
How is transferrin saturation calculated from transferrin? +
Transferrin saturation (%) = serum iron / (transferrin × 25.12) × 100. Alternatively from TIBC: serum iron / TIBC × 100. Normal: 20–45%. < 16%: iron-deficient erythropoiesis; > 45%: iron overload (suspect hemochromatosis). Transferrin correlates closely with TIBC (total iron-binding capacity).
Why does inflammation affect the transferrin measurement? +
Transferrin is a negative acute-phase reactant: during inflammation, liver production of transferrin decreases (similar to albumin), while positive acute-phase proteins (CRP, ferritin) rise. This can mask iron deficiency with concurrent inflammation — ferritin may appear falsely normal despite actual iron deficiency.
Sources
Last Reviewed: May 28, 2026 · sina
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.