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 |
Agree on your personal target range with your doctor.
↓ 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).
✓ What can influence this value
The transferrin value is influenced by iron status (it rises with iron deficiency and falls with iron overload), inflammation (transferrin is a negative acute-phase marker), liver function as the site of synthesis, protein supply and malnutrition, and pregnancy. It is therefore considered together with ferritin and transferrin saturation. The assessment is made by the treating doctor.
When to test
Transferrin is usually measured together with ferritin and serum iron, from which transferrin saturation is calculated, for example when investigating anemia or iron deficiency, when hemochromatosis is suspected, or with chronic inflammation or liver disease. On its own, transferrin is of limited informative value.
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 (suspected 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.
Transferrin
Sources
Last updated: May 28, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.