Lab result explainedVitamins and mineralsLast updated November 10, 2026

Transferrin blood test: what high and low transferrin levels mean

Transferrin · Iron studies (iron panel) · reported in mg/dL (SI: g/L; 1 g/L = 100 mg/dL)

Transferrin is the protein that carries iron through your bloodstream. It is made by the liver, each molecule can hold two atoms of iron, and at any moment it is delivering iron from the gut and from recycled red cells to the bone marrow, where most of it goes into new hemoglobin. A transferrin blood test measures how much of this carrier protein you have, reported in milligrams per decilitre; the typical adult range is about 200 to 360 mg/dL, with some variation between laboratories.

Transferrin is part of the iron studies panel and is best read together with serum iron, ferritin and the transferrin saturation. The liver makes more transferrin when iron is scarce, so a high level is the classic signature of iron deficiency, and it also rises in pregnancy and with estrogen. A low level means the liver is making less or you are losing it: inflammation and chronic disease, cirrhosis, malnutrition, protein loss through the kidneys, and iron overload (where the body deliberately turns transferrin down) are the main causes.

Two related numbers often appear on the same report. Total iron-binding capacity (TIBC) is essentially the same measurement expressed as how much iron the blood could carry; TIBC in µg/dL is roughly transferrin in mg/dL multiplied by 1.25. Transferrin saturation is serum iron divided by that capacity: normally 20 to 50 percent, under about 16 to 20 percent in iron deficiency and over 45 percent when iron overload needs ruling out.

Transferrin at a glance

  • What it is: the liver-made protein that binds and transports iron in blood; normally about 30 percent of its binding sites are occupied.
  • Normal (adults): about 200–360 mg/dL (2.0–3.6 g/L); labs differ. TIBC, the same thing expressed as iron-carrying capacity, is about 250–450 µg/dL.
  • High transferrin (above about 360 mg/dL): usually iron deficiency; also pregnancy, oral contraceptives and estrogen therapy.
  • Low transferrin (below about 200 mg/dL): inflammation or chronic illness, liver disease, malnutrition, nephrotic syndrome, or iron overload such as hemochromatosis.
  • Transferrin saturation = serum iron ÷ TIBC × 100; 20–50 percent is normal, under 16–20 percent suggests iron deficiency, over 45 percent prompts a check for iron overload.
  • Next step: read it with ferritin, serum iron, saturation, hemoglobin and CRP; iron deficiency needs a cause found (bleeding, diet, malabsorption) and treated, and a high saturation leads to HFE gene testing.

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What Transferrin measures

Transferrin is an 80 kDa glycoprotein synthesised mainly by liver cells, with a half-life of about 8 days. The plasma iron pool it carries is tiny, 3 to 4 mg, but it turns over roughly ten times a day to deliver the 20 to 25 mg of iron the bone marrow needs for new red cells. Cells take up iron by capturing iron-loaded transferrin through transferrin receptors on their surface. Keeping iron bound to transferrin also matters for safety: free iron generates damaging free radicals and feeds bacteria, so the body normally keeps saturation well below 100 percent.

The laboratory measures transferrin directly by immunoassay (nephelometry or turbidimetry). TIBC is measured differently, by saturating a sample with iron and measuring how much is bound, but the two are tightly related and some labs calculate one from the other. Transferrin synthesis rises when liver iron stores fall and drops when they are replete, which is what makes it a useful iron marker, but it is also a negative acute-phase protein: the liver reduces production during infection, inflammation and injury, and when protein and calories are short. The result is that transferrin can look normal in iron deficiency that coexists with inflammation.

A few related tests are easy to confuse with it. Soluble transferrin receptor rises in iron deficiency and is not affected by inflammation, which makes it useful when ferritin and transferrin are ambiguous. Carbohydrate-deficient transferrin is a marker of heavy alcohol use over the preceding two to three weeks, not of iron. Beta-2 transferrin is a form found only in cerebrospinal fluid and is used to confirm a CSF leak from the nose or ear. Iron studies are ideally drawn in the morning, fasting, and not on the day of an iron tablet or within a week of an iron infusion.

Normal range for Transferrin

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

GroupTypical range (mg/dL (SI: g/L; 1 g/L = 100 mg/dL))Notes
Adults, typical laboratory rangeAbout 200–360 mg/dLRanges quoted by different labs include 212–360, 204–360 and 180–340 mg/dL. Use the printed range.
Newborns and infantsLower, roughly 130–275 mg/dL at birth, rising toward adult values during the first yearChildren from about age 1 to 16 have ranges close to adults.
PregnancyRises progressively, often to 300–450 mg/dL by the third trimesterEstrogen-driven and expected; a high transferrin in pregnancy is not by itself evidence of iron deficiency, so ferritin is used.
Equivalent TIBCAbout 250–450 µg/dLTIBC (µg/dL) is approximately transferrin (mg/dL) × 1.25; the two track each other.
Transferrin saturation20–50 percent (men); 15–50 percent (women)Below 16–20 percent suggests iron deficiency; above 45 percent should prompt ferritin and HFE testing for hemochromatosis.
As a nutrition marker150–200 mg/dL mild, 100–150 moderate, below 100 severe protein-calorie malnutritionOlder cut-offs still used in hospital nutrition assessment; inflammation lowers transferrin independently of nutrition.
Iron deficiency patternTransferrin above 360 (TIBC above 450) with serum iron low, saturation under 16 percent and ferritin under 30 ng/mLThe combination is diagnostic; a borderline ferritin of 30–100 with inflammation can still be iron deficiency.
Anemia of inflammation patternTransferrin low or low-normal, serum iron low, saturation low-normal, ferritin normal or highIron is present but locked away by hepcidin; iron tablets do not help.
Iron overload patternTransferrin low-normal, saturation above 45 percent (often above 60), ferritin highHereditary hemochromatosis, transfusions, or ineffective red cell production (thalassemia, myelodysplasia).

High transferrin

A high transferrin, or a high TIBC, means your liver is making extra iron carrier, and the usual reason is that iron stores are low. When ferritin falls, hepatocytes up-regulate transferrin synthesis, so the typical iron-deficiency panel is a high transferrin, low serum iron, a saturation under 16 to 20 percent and a ferritin under 30 ng/mL, often with a low hemoglobin, small red cells (low MCV) and a high RDW. Transferrin can rise before anemia develops, which makes it an early marker in people losing iron faster than they absorb it.

The other common causes are hormonal rather than iron-related. Transferrin rises steadily through pregnancy, reaching 50 percent above baseline by the third trimester, and oral contraceptives and estrogen replacement push it up by a smaller amount. In these situations a high transferrin is expected and ferritin is the better guide to iron stores. Rarely, acute viral hepatitis raises transferrin for a few weeks as liver cells regenerate.

Once iron deficiency is confirmed, the important question is why. Menstrual loss, pregnancy and growth explain most cases in women under 50 and in teenagers. In men and in post-menopausal women, blood loss from the gut (ulcers, aspirin and anti-inflammatory use, polyps, colorectal cancer, celiac disease, inflammatory bowel disease) must be considered, and guidelines recommend endoscopy and colonoscopy in these groups unless another cause is obvious.

Common causes

  1. Iron deficiency from blood loss

    Heavy periods, gastrointestinal bleeding (ulcers, NSAIDs, polyps, cancer, hemorrhoids), frequent blood donation and chronic nosebleeds drain iron faster than diet replaces it; transferrin rises as ferritin falls below about 30 ng/mL.

  2. Low dietary iron

    Vegetarian and vegan diets, restrictive eating and diets of mostly refined carbohydrates supply little absorbable (heme) iron; infants on cow's milk and toddlers who drink large volumes of milk are classic examples.

  3. Malabsorption

    Celiac disease, H. pylori gastritis, atrophic gastritis, gastric bypass, inflammatory bowel disease and long-term acid-suppressing drugs all reduce iron absorption; celiac disease is found in 3 to 5 percent of unexplained iron deficiency.

  4. Pregnancy and rapid growth

    Pregnancy needs about 1,000 mg of extra iron and raises transferrin regardless; growth spurts, adolescence and endurance training also increase demand.

  5. Estrogen: oral contraceptives and hormone therapy

    Estrogen stimulates hepatic transferrin synthesis, raising transferrin and TIBC by 10 to 20 percent without any change in iron stores.

  6. Treated polycythemia vera or frequent phlebotomy

    Repeated blood removal deliberately produces iron deficiency, so transferrin is expected to be high in these patients.

  7. Acute viral hepatitis

    Regenerating liver tissue can transiently increase transferrin output; the picture clears as liver enzymes settle.

Symptoms that can go with it

  • Tiredness, low energy and reduced exercise tolerance from iron deficiency, with or without anemia
  • Shortness of breath on exertion, palpitations and pale skin or inner eyelids
  • Restless legs, especially at night
  • Hair shedding, brittle or spoon-shaped nails, and a sore or smooth tongue
  • Craving ice, clay or starch (pica) and cold hands and feet
  • Headaches, poor concentration and dizziness on standing
  • No symptoms at all when the rise is from pregnancy or estrogen

Low transferrin

A low transferrin (or low TIBC) means the liver is making less carrier protein or you are losing it, and it is less specific than a high value. The most frequent cause is inflammation: infection, autoimmune disease, cancer, surgery and even obesity-related inflammation switch down transferrin production within days, which is why transferrin falls alongside albumin in anyone who is ill. In this setting a low transferrin says more about the illness than about iron, and ferritin, which rises with inflammation, tells the opposite story.

The second group of causes reflects the liver and protein status. Cirrhosis and other chronic liver disease reduce synthesis; protein-calorie malnutrition, anorexia and the weeks after major surgery lower it enough that transferrin has long been used as a nutrition marker, with values under 200 mg/dL graded as mild and under 100 as severe depletion. Nephrotic syndrome and protein-losing enteropathy lose transferrin into urine or stool. Glucocorticoids and testosterone also lower it modestly.

The cause not to miss is iron overload. When iron stores are full the liver reduces transferrin, so hemochromatosis typically shows a low-normal transferrin with a transferrin saturation above 45 percent (often above 60) and a high ferritin. The saturation, not the transferrin itself, is the screening number, and a value above 45 percent on a fasting sample leads to HFE gene testing. Extremely rarely, transferrin is almost absent from birth (atransferrinemia), causing severe anemia with iron overload.

Common causes

  1. Infection, inflammation and chronic disease

    Interleukin-6 and other cytokines suppress hepatic transferrin production; it falls within days of an infection, surgery or a flare of rheumatoid arthritis, inflammatory bowel disease or lupus, and stays low in chronic conditions and many cancers.

  2. Chronic liver disease

    Cirrhosis, alcohol-related liver disease and advanced fatty liver reduce synthesis of transferrin and albumin together; the fall tracks the severity of liver dysfunction.

  3. Malnutrition and protein deficiency

    With a half-life of 8 days, transferrin responds within two weeks to inadequate protein and calories; eating disorders, prolonged illness and post-operative starvation lower it.

  4. Nephrotic syndrome and protein-losing enteropathy

    Transferrin is small enough to leak through damaged glomeruli or inflamed bowel; heavy urinary protein loss causes both low transferrin and, over time, iron deficiency.

  5. Iron overload

    Hereditary hemochromatosis, repeated transfusions, iron infusions and the ineffective red cell production of thalassemia or myelodysplasia fill iron stores; the liver responds by making less transferrin and saturation climbs above 45 percent.

  6. Chronic kidney disease

    Inflammation, reduced protein intake and uremia lower transferrin in advanced CKD and dialysis; iron deficiency is still common and is judged by saturation and ferritin together.

  7. Hemolytic anemia and ineffective erythropoiesis

    Conditions that release large amounts of iron from destroyed or abnormal red cells keep stores high and transferrin low.

  8. Glucocorticoids and testosterone

    Prednisone and anabolic steroids modestly reduce hepatic transferrin synthesis; the effect reverses when they are stopped.

  9. Congenital atransferrinemia

    A very rare inherited absence of transferrin (fewer than 20 reported families) causing severe microcytic anemia and iron deposition in organs from infancy.

Symptoms that can go with it

  • Often none from the low transferrin itself; symptoms belong to the cause
  • Fever, fatigue, joint pain or weight loss with inflammation or chronic disease
  • Swelling of the ankles and around the eyes, and frothy urine, with nephrotic syndrome
  • Jaundice, abdominal swelling, easy bruising or spider veins with liver disease
  • Muscle wasting, weakness and weight loss with malnutrition
  • Joint pain in the knuckles, fatigue, bronzed skin, diabetes or erectile dysfunction with iron overload
  • Anemia symptoms (tiredness, breathlessness) when inflammation blocks iron use

Read it alongside

  • Ferritin — the best single measure of iron stores; under 30 ng/mL means deficiency, while a high ferritin with low transferrin points to inflammation or overload.
  • Serum iron — low in both iron deficiency and inflammation, high in overload; it swings with meals and time of day, so it is read only with transferrin and ferritin.
  • Transferrin saturation (iron saturation) — the key ratio: under 16–20 percent in deficiency, above 45 percent in overload.
  • TIBC — the same information as transferrin expressed as iron-binding capacity (roughly transferrin × 1.25).
  • Hemoglobin, MCV and RDW — show whether iron deficiency has progressed to anemia and whether red cells are small and variable.
  • CRP — any rise explains a low transferrin and a raised ferritin at the same time, and means iron deficiency may be hidden.
  • Albumin and total protein — fall with transferrin in liver disease, malnutrition and nephrotic syndrome.
  • Reticulocyte count and reticulocyte hemoglobin — a low reticulocyte hemoglobin confirms iron-restricted red cell production even when ferritin is equivocal.

What usually happens next

  1. A high transferrin with low ferritin confirms iron deficiency; the next question is the source, which in men and post-menopausal women usually means stool testing and gastroscopy with colonoscopy, and in women under 50 a review of menstrual loss and diet, plus celiac serology.
  2. A low transferrin is first read with CRP and albumin; if inflammation or liver disease explains it, no iron-specific action is needed, but if transferrin saturation is above 45 percent, ask for a fasting repeat and HFE gene testing.
  3. If iron deficiency is confirmed, oral iron (often 60 to 100 mg of elemental iron daily or on alternate days) is standard, with a hemoglobin rise of about 1 to 2 g/dL expected within four weeks and iron studies repeated after about three months; intravenous iron is used when tablets fail or are not absorbed.
  4. Ask for iron studies to be drawn in the morning, fasting, not on a day you have taken an iron tablet, and at least a week after any iron infusion; estrogen therapy, pregnancy and recent illness should be noted on the request.
  5. If transferrin is low because of malnutrition, a dietitian review and repeat in two to three weeks tracks response; transferrin rises faster than albumin when protein intake improves.

Diet, lifestyle and natural levers with evidence

What can move Transferrin once the cause is known. Nothing here replaces finding the cause.

Correct iron deficiency with iron, and transferrin follows

Strong evidence

Transferrin normalizes as iron stores refill. In trials of oral iron for iron-deficiency anemia, hemoglobin rises about 1 to 2 g/dL within four weeks and ferritin and transferrin return toward normal over three months. A 2017 study using stable isotopes showed that taking 60 mg of iron on alternate days was absorbed about 30 to 50 percent better per dose than daily dosing, with fewer stomach side effects, because each dose raises hepcidin for 24 hours. Ferrous sulfate, gluconate and fumarate all work; what matters is elemental iron dose and consistency.

Do not take iron without a confirmed deficiency: it is harmful in hemochromatosis and useless in anemia of inflammation. Iron causes constipation and dark stools, and large doses are dangerous to young children.

Choose iron-rich foods in absorbable forms

Moderate evidence

Heme iron from red meat, poultry, fish and shellfish is absorbed at 15 to 35 percent, while non-heme iron from beans, lentils, tofu, spinach and fortified grains is absorbed at 2 to 20 percent depending on what is eaten with it. Three ounces of beef supply about 2 mg of mostly heme iron, a cup of cooked lentils 6.6 mg of non-heme iron, and a cup of fortified cereal 8 to 18 mg. Eating meat, fish or poultry with a plant-based meal roughly doubles non-heme iron absorption from that meal.

Move tea, coffee and calcium away from iron-rich meals

Moderate evidence

Absorption studies show a cup of tea with a meal cuts non-heme iron absorption by 60 to 90 percent and coffee by about 40 percent, through polyphenols; waiting an hour largely removes the effect. Calcium supplements and large dairy servings taken with iron reduce absorption by up to 50 percent. Vitamin C-rich foods increase non-heme iron absorption two- to threefold in single-meal studies, although a 2020 randomised trial found that adding 100 mg of vitamin C to iron tablets did not improve hemoglobin response in people with iron-deficiency anemia, so it is not essential with supplements.

Restore protein and calories when transferrin is low from malnutrition

Moderate evidence

Transferrin's 8-day half-life makes it one of the faster markers of nutritional recovery: in studies of hospital refeeding and enteral nutrition, transferrin rose significantly within two weeks of meeting protein targets (about 1.2 to 1.5 g of protein per kilogram a day in illness), well before albumin changed. This only applies when low protein intake is the cause; where inflammation is driving the low transferrin, feeding does not raise it until the inflammation settles.

Refeeding after severe malnutrition can cause dangerous shifts in phosphate, potassium and magnesium and should be supervised.

Limit alcohol and treat the liver condition

Preliminary evidence

Alcohol both lowers transferrin synthesis in a damaged liver and increases iron absorption, so heavy drinkers often show a low transferrin with a high ferritin and saturation that can mimic hemochromatosis. Observational studies show ferritin and saturation fall and transferrin recovers over weeks to months of abstinence as liver function improves. Carbohydrate-deficient transferrin, a separate test, rises with more than about four to five drinks a day for two weeks and normalizes after two to four weeks of abstinence.

When to see a clinician promptly

  • Black, tarry or bloody stools, vomiting blood, or iron deficiency in a man or a post-menopausal woman: possible gastrointestinal bleeding, needs prompt investigation and same-day care if bleeding is active.
  • Chest pain, severe breathlessness, fainting or a racing heartbeat with anemia symptoms: severe anemia can strain the heart.
  • Unexplained weight loss, change in bowel habit or abdominal pain alongside iron deficiency, which raise the possibility of bowel cancer, celiac disease or inflammatory bowel disease.
  • Transferrin saturation above 45 percent with a high ferritin, especially with joint pain, fatigue, diabetes or liver test abnormalities: iron overload is treatable and early treatment prevents organ damage.
  • Low transferrin with swelling of the legs or face and frothy urine, or with jaundice and abdominal swelling: kidney or liver disease needing evaluation.
  • No response to three months of iron tablets, which suggests ongoing blood loss, malabsorption or a wrong diagnosis.

Frequently asked questions

What is a normal transferrin level?

About 200 to 360 mg/dL (2.0 to 3.6 g/L) in adults, though laboratories quote slightly different ranges, such as 212 to 360 or 180 to 340 mg/dL. Newborns run lower and pregnant women higher, often 300 to 450 mg/dL in the third trimester. The equivalent TIBC range is roughly 250 to 450 µg/dL.

What does low transferrin mean?

The liver is making less carrier protein or you are losing it. The common causes are inflammation and chronic illness (infection, autoimmune disease, cancer), liver disease, malnutrition and protein loss through the kidneys or gut. Iron overload also lowers it, which is why a low transferrin with a transferrin saturation above 45 percent and a high ferritin should prompt testing for hemochromatosis. On its own, a mildly low transferrin in someone who has been unwell is usually not important.

What does high transferrin mean?

Most often iron deficiency: the liver makes more transferrin when iron stores run low, so a high transferrin usually comes with a low ferritin, a low serum iron and a saturation under 16 to 20 percent. Pregnancy, oral contraceptives and estrogen therapy also raise it without any iron problem. If iron deficiency is confirmed, the next step is finding where the iron is going: menstrual loss, diet, malabsorption or gut bleeding.

What is the difference between transferrin and TIBC?

They measure the same thing from two angles. Transferrin is the carrier protein itself, measured directly in mg/dL. Total iron-binding capacity (TIBC) is how much iron the blood could carry if every transferrin molecule were fully loaded, measured in µg/dL; TIBC is approximately transferrin × 1.25. Some labs report one, some both, and some calculate TIBC from transferrin. High transferrin and high TIBC mean the same thing: usually iron deficiency.

What is transferrin saturation and what should it be?

It is the percentage of transferrin's iron-binding sites that are actually carrying iron, calculated as serum iron divided by TIBC (or transferrin × 1.25) times 100. Normal is about 20 to 50 percent. Below 16 to 20 percent suggests iron deficiency, and above 45 percent on a fasting morning sample is the threshold at which guidelines recommend checking ferritin and HFE genes for hereditary hemochromatosis.

Can low transferrin mean iron overload?

Yes. When iron stores are full the liver reduces transferrin production, so hemochromatosis and transfusion-related overload typically show a low-normal transferrin alongside a saturation above 45 to 60 percent and a high ferritin. Low transferrin alone is not diagnostic, because inflammation and liver disease cause the same fall; it is the combination with high saturation and ferritin that matters.

Why is transferrin high in pregnancy?

Estrogen stimulates the liver to make more transferrin, and the body is also preparing to move about 1,000 mg of extra iron to the baby and placenta. Transferrin and TIBC rise steadily from the first trimester and can be 50 percent above baseline by the third. Because of this, a high transferrin in pregnancy does not prove iron deficiency; ferritin (under 30 ng/mL) and hemoglobin are used instead.

Do I need to fast for a transferrin test?

Transferrin itself changes little with food, but it is almost always drawn as part of iron studies, and serum iron and saturation vary with meals and time of day. The standard advice is a morning sample after an overnight fast, no iron tablet that morning, and at least a week after any iron infusion. Mention pregnancy, estrogen-containing medicines and any recent illness, all of which shift the result.

References

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  6. Kowdley KV, Brown KE, Ahn J, Sundaram V. ACG clinical guideline: hereditary hemochromatosis. American Journal of Gastroenterology (2019)
  7. Gkouvatsos K, Papanikolaou G, Pantopoulos K. Regulation of iron transport and the role of transferrin. Biochimica et Biophysica Acta (2012)
  8. Stoffel NU, Cercamondi CI, Brittenham G, et al.. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematology (2017)
  9. Hurrell R, Egli I. Iron bioavailability and dietary reference values. American Journal of Clinical Nutrition (2010)
  10. Li N, Zhao G, Wu W, et al.. The efficacy and safety of vitamin C for iron supplementation in adult patients with iron deficiency anemia: a randomized clinical trial. JAMA Network Open (2020)
  11. Keller U. Nutritional laboratory markers in malnutrition. Journal of Clinical Medicine (2019)
  12. Iron deficiency. Merck Manual Professional Version (2024)

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.