Transferrin
Also known as: Siderophilin
What Does Transferrin Measure?
Transferrin is a glycoprotein produced primarily by the liver that serves as the main carrier of iron in the bloodstream. This biomarker measures the concentration of this transport protein in your blood, reflecting the body's iron-carrying capacity. Each transferrin molecule can bind up to two iron atoms, ferrying iron from sites of absorption in the intestine and iron recycling in the spleen to tissues that need it, most importantly the bone marrow for red blood cell production.
Why Does Transferrin Matter?
Transferrin levels are a critical indicator of iron metabolism and nutritional status. When iron stores are depleted, the liver produces more transferrin as a compensatory mechanism, making elevated transferrin a classic sign of iron deficiency anemia. Conversely, low transferrin levels can indicate liver disease, malnutrition, or chronic inflammatory conditions, since the liver's ability to synthesize proteins is compromised. Clinicians often evaluate transferrin alongside other iron studies — such as serum iron, ferritin, and transferrin saturation — to distinguish between different types of anemia and to monitor treatment responses.
Normal Ranges
Males
215–365 mg/dL (2.15–3.65 g/L)
Females
215–380 mg/dL (2.15–3.80 g/L)
Children
Varies by age; typically 200–360 mg/dL in school-age children
Causes of High Levels
- Iron deficiency anemia — the liver upregulates transferrin production to maximize iron capture
- Pregnancy — increased iron demand stimulates higher transferrin synthesis
- Estrogen therapy or oral contraceptive use — estrogens stimulate hepatic transferrin production
- Polycythemia vera — elevated red cell mass increases iron utilization and raises transferrin
- Chronic blood loss (e.g., heavy menstruation, gastrointestinal bleeding) — ongoing iron depletion drives compensatory increase
Causes of Low Levels
- Liver disease (cirrhosis, hepatitis) — impaired hepatic protein synthesis reduces transferrin production
- Malnutrition or protein-energy deficiency — insufficient amino acid supply limits synthesis
- Chronic inflammatory conditions and infections — inflammation suppresses transferrin as part of the acute-phase response
How to Improve Your Transferrin
Diet
- Consume iron-rich foods such as lean red meat, poultry, and seafood to support healthy iron metabolism
- Eat plant-based iron sources (lentils, spinach, tofu, fortified cereals) paired with vitamin C to enhance non-heme iron absorption
- Avoid drinking tea or coffee with iron-rich meals as tannins inhibit iron absorption and can dysregulate transferrin levels
- Ensure adequate protein intake (0.8–1.2 g/kg body weight daily) from high-quality sources to support liver synthesis of transferrin
- Limit alcohol consumption, which can impair liver function and reduce hepatic protein production including transferrin
Supplements
- Iron supplementation (ferrous sulfate 325 mg or ferrous gluconate 240 mg once daily) for confirmed iron deficiency after medical consultation
- Vitamin C (250–500 mg taken with iron supplements) to significantly improve non-heme iron absorption
- Vitamin B12 (1,000 mcg daily) and folate (400–800 mcg daily) if co-existing nutritional anemia is present
- Whey or plant-based protein supplements if dietary protein intake is insufficient to support liver function
Related Biomarkers
Frequently Asked Questions
What is the difference between transferrin and ferritin?
Transferrin and ferritin both relate to iron metabolism but serve different roles. Transferrin is a transport protein that actively carries iron through the bloodstream to tissues that need it. Ferritin, on the other hand, is a storage protein that holds iron reserves inside cells, particularly in the liver, spleen, and bone marrow. Serum ferritin reflects how much iron is stored in the body, while transferrin reflects how much iron-carrying capacity is available. In iron deficiency, ferritin falls (depleted stores) and transferrin rises (the body compensates by making more carrier). In chronic disease or inflammation, ferritin can be falsely elevated while transferrin is suppressed.
What does a high transferrin level mean?
A high transferrin level most commonly signals that the body is iron-deficient and is trying to compensate by producing more iron-transport protein to capture every available iron molecule. The liver increases transferrin synthesis when it senses low iron availability. High transferrin can also occur during pregnancy or with estrogen use. Importantly, a high transferrin level alone does not confirm iron deficiency anemia — your doctor will also look at transferrin saturation (which would be low in true deficiency), serum iron, and ferritin to confirm the diagnosis.
What does a low transferrin level mean?
Low transferrin levels typically indicate a problem with the liver's ability to synthesize proteins, a condition associated with protein malnutrition, or the body's acute-phase response to chronic illness or inflammation. Since transferrin is made in the liver, conditions like cirrhosis, hepatitis, or severe malnutrition reduce its production. Chronic inflammatory diseases, infections, and cancers also suppress transferrin as part of the body's inflammatory response. Paradoxically, iron overload conditions like hemochromatosis can also lower transferrin levels because the body downregulates the protein when iron is in excess.