Lab result explainedVitamins and mineralsLast updated November 8, 2026

TIBC blood test: what high and low total iron-binding capacity mean

Total iron-binding capacity (TIBC) · Iron panel (serum iron, TIBC, transferrin saturation, ferritin) · reported in µg/dL (micrograms per decilitre); some labs use µmol/L (1 µmol/L = 5.58 µg/dL). Transferrin is reported in mg/dL or g/L.

Total iron-binding capacity (TIBC) measures how much iron your blood could carry if every available binding site were filled. Almost all of that capacity belongs to transferrin, the protein your liver makes to ferry iron from the gut and from stores to the bone marrow, so TIBC is essentially an indirect measure of transferrin. Normal is about 250 to 450 µg/dL. The liver makes more transferrin when the body is short of iron and less when iron is plentiful or when there is inflammation, so TIBC moves in the opposite direction to your iron stores.

That inverse relationship is what makes the test useful. A high TIBC with a low serum iron and a low ferritin is the classic signature of iron deficiency: the body is holding out more empty seats for an iron supply that is not arriving. A low TIBC with a low serum iron and a normal or high ferritin is the signature of anemia of chronic disease, where iron is present but locked in storage by inflammation. A low or low-normal TIBC with a high serum iron and a high ferritin suggests iron overload, including hereditary hemochromatosis.

TIBC is rarely interpreted on its own. Dividing serum iron by TIBC gives transferrin saturation, the percentage of binding sites actually carrying iron, and that figure, together with ferritin, is how clinicians decide between deficiency, inflammation and overload. Pregnancy and estrogen raise TIBC without any iron problem, and liver disease, malnutrition and kidney protein loss lower it, so the whole panel, and the person's situation, are read together.

TIBC at a glance

What it is: the total amount of iron the blood's transport protein (transferrin) can bind; an indirect measure of transferrin and of how hungry the body is for iron.
Normal (adults): about 250–450 µg/dL (45–81 µmol/L); some labs use 240–450 or 262–474. Transferrin itself is about 200–360 mg/dL.
High TIBC (above about 450 µg/dL) most often means iron deficiency; also pregnancy, estrogen-containing medication and, occasionally, acute hepatitis.
Low TIBC (below about 250 µg/dL) means inflammation or chronic disease, iron overload (hemochromatosis, repeated transfusions), malnutrition, liver disease or protein loss through the kidneys.
Read it with serum iron and ferritin: high TIBC + low iron + ferritin below 30 ng/mL = iron deficiency; low TIBC + low iron + ferritin above 100 = anemia of inflammation; low TIBC + high iron + high ferritin = iron overload.
Next step: transferrin saturation and ferritin if not already done, a CRP to check for inflammation, and for iron deficiency in men and post-menopausal women, a search for the source of blood loss.

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What TIBC measures

Transferrin is a protein made by the liver that binds two atoms of iron per molecule and carries them through the blood to cells that display transferrin receptors, chiefly red cell precursors in the marrow. At any moment only about 20 to 45 percent of transferrin's binding sites are occupied; the rest is spare capacity. TIBC measures the total (occupied plus spare) by saturating a serum sample with excess iron, removing the unbound surplus and measuring what the proteins hold. Some laboratories measure the unsaturated iron-binding capacity (UIBC) directly and add serum iron to it, or measure transferrin by immunoassay and convert it (TIBC in µg/dL is roughly transferrin in mg/dL multiplied by 1.25 to 1.4).

The liver adjusts transferrin production to the body's iron state. When stores run low, hepatocytes make more transferrin, so TIBC rises, typically above 400 to 450 µg/dL in established iron deficiency. When stores are high, or when inflammatory cytokines are circulating, production falls; transferrin is a negative acute-phase protein, so infection, surgery, autoimmune disease and cancer all lower TIBC within days, regardless of iron status. Estrogen stimulates transferrin synthesis, which is why TIBC rises in pregnancy and on the combined pill.

TIBC changes slowly, over one to two weeks, because transferrin has a half-life of about 8 to 10 days, so it is more stable than serum iron, which swings by 20 to 30 percent through the day and jumps for hours after an iron tablet or a red-meat meal. Fasting is not strictly required for TIBC, but because it is usually drawn with serum iron for the saturation calculation, a morning fasting sample with iron supplements held for 24 hours gives the most reliable panel.

Normal range for TIBC

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

Group	Typical range (µg/dL (micrograms per decilitre); some labs use µmol/L (1 µmol/L = 5.58 µg/dL). Transferrin is reported in mg/dL or g/L.)	Notes
Adults, normal TIBC	About 250–450 µg/dL (45–81 µmol/L)	Labs differ: 240–450, 255–450 and 262–474 are all in use. Use the range on your report.
Serum iron, normal	About 60–170 µg/dL (men slightly higher than women)	Highest in the morning; falls by up to 30 percent through the day; raised for hours after an iron tablet.
Unsaturated iron-binding capacity (UIBC)	About 150–375 µg/dL	TIBC minus serum iron; the empty seats. High in iron deficiency, low in overload.
Transferrin, normal	About 200–360 mg/dL (2.0–3.6 g/L)	TIBC ≈ transferrin × 1.25–1.4. Transferrin below 200 mg/dL is also used as a marker of protein malnutrition.
Iron deficiency pattern	TIBC above about 400–450 µg/dL, serum iron below 60, saturation below 15–20%, ferritin below 30 ng/mL	TIBC is often the last marker to change; ferritin falls first.
Anemia of inflammation pattern	TIBC below about 250–300 µg/dL, serum iron low, saturation below 20%, ferritin above 100 ng/mL	Transferrin falls as a negative acute-phase reactant while ferritin rises as a positive one.
Iron overload pattern	TIBC low-normal or low, serum iron above 170, saturation above 45%, ferritin above 300 (men) or 200 (women) ng/mL	Hereditary hemochromatosis, repeated transfusions, ineffective erythropoiesis, chronic liver disease.
Pregnancy (second and third trimester)	TIBC rises to about 450–550 µg/dL	Estrogen-driven; saturation falls. Ferritin, not TIBC, is used to judge iron stores in pregnancy.

High TIBC

A high TIBC means your liver is making more transferrin than usual, and in most adults who are not pregnant that is because the body senses it is short of iron. The pattern is a TIBC above about 400 to 450 µg/dL with a serum iron below 60 µg/dL, a transferrin saturation below 15 to 20 percent and a ferritin below 30 ng/mL (or below 45 if there is any inflammation). TIBC is a late marker: ferritin falls first as stores empty, then serum iron and saturation drop, then TIBC rises, and only then do hemoglobin and MCV fall. A high TIBC with a normal hemoglobin therefore catches iron deficiency before it becomes anemia.

Finding iron deficiency is the start, not the end. In menstruating women heavy periods are the usual explanation; in pregnancy the demand of the growing fetus and placenta outstrips intake; in men and post-menopausal women, iron deficiency means blood is being lost somewhere, most often the gastrointestinal tract, and guidelines recommend examining the upper and lower gut because the cause can be an ulcer, inflammatory bowel disease, celiac disease or a cancer. Poor absorption from celiac disease, Helicobacter pylori infection, bariatric surgery or long-term acid suppression is the other main group of causes.

A high TIBC without iron deficiency happens in pregnancy and with estrogen (the combined contraceptive pill, oral hormone therapy), where transferrin synthesis is stimulated directly and ferritin is normal. Acute viral hepatitis can also release transferrin and raise TIBC transiently. In these cases serum iron is usually normal and saturation is normal or only mildly low.

Common causes

Iron deficiency from blood loss
Heavy menstrual bleeding, slow bleeding from ulcers, gastritis, polyps, bowel cancer, hemorrhoids or inflammatory bowel disease, aspirin or NSAID use, and frequent blood donation (each unit removes about 200 to 250 mg of iron). The liver raises transferrin as ferritin falls.
Iron deficiency from low intake
Vegetarian and vegan diets without planning, restrictive eating, toddlers on large volumes of cow's milk, and diets high in tea and unleavened whole-grain bread (phytates) limit absorbable iron. Non-heme iron is absorbed at only 2 to 20 percent.
Iron deficiency from poor absorption
Celiac disease (iron is absorbed in the duodenum, the part most damaged), Helicobacter pylori infection, atrophic gastritis, gastric bypass or sleeve surgery, long-term proton pump inhibitors and inflammatory bowel disease all reduce uptake.
Pregnancy
Estrogen raises transferrin production from the second trimester, and the fetus, placenta and expanded red cell mass need about 1,000 mg of extra iron over the pregnancy. TIBC commonly reaches 450 to 550 µg/dL; ferritin is the better guide to stores.
Estrogen-containing medication
Combined oral contraceptives and oral hormone replacement therapy stimulate hepatic transferrin synthesis, raising TIBC by 10 to 20 percent with a normal ferritin.
Increased demand
Rapid growth in infancy and adolescence, endurance training (through gut blood loss, foot-strike hemolysis and exercise-induced hepcidin) and recovery from blood loss or from B12 or folate treatment all draw on iron and raise transferrin.
Acute hepatitis
Inflamed hepatocytes can release transferrin and iron, producing a transient rise in TIBC and serum iron that settles as the liver recovers.
Polycythemia vera
The overactive marrow consumes iron faster than it is absorbed, so people with polycythemia vera often develop iron deficiency with a high TIBC, especially after repeated venesection.

Symptoms that can go with it

Often none in early iron deficiency before hemoglobin falls
Tiredness, low energy and poor exercise tolerance
Breathlessness on exertion and a pounding heart
Pale skin, brittle or spoon-shaped nails, hair shedding
Cravings for ice, clay or starch (pica) and restless legs at night
Sore or smooth tongue, cracks at the corners of the mouth, difficulty swallowing
Headaches, poor concentration and feeling cold
Heavy periods, black stools or other signs of the source of blood loss

Low TIBC

A low TIBC means the liver is making less transferrin, and the most common reason is inflammation. Transferrin is a negative acute-phase protein: infection, surgery, autoimmune disease, heart failure, chronic kidney disease, obesity and cancer all push it down within days, while ferritin, a positive acute-phase protein, goes up. The result is the pattern of anemia of chronic disease (anemia of inflammation): low serum iron, low TIBC, saturation below 20 percent and ferritin above 100 ng/mL. Iron is present but locked in storage cells by the hormone hepcidin, so iron tablets do not help and the treatment is the underlying condition.

The second important cause is iron overload. When stores are full the liver has no reason to make much transferrin, so TIBC sits low or low-normal while serum iron and ferritin are high and saturation exceeds 45 percent. In hereditary hemochromatosis, which affects about 1 in 200 to 300 people of Northern European ancestry, this pattern is the first laboratory clue and leads to HFE gene testing. Repeated blood transfusions, chronic liver disease (alcohol, hepatitis C, fatty liver), and conditions where red cell production is ineffective (thalassemia, myelodysplasia, sideroblastic anemia) produce the same picture.

Because transferrin is a protein made by the liver and small enough to be lost through damaged kidneys, a low TIBC also occurs in protein-calorie malnutrition (transferrin below 200 mg/dL is used as a nutritional marker in hospital), cirrhosis and advanced liver disease, nephrotic syndrome (where transferrin leaks into the urine) and protein-losing bowel disease. In these states the low TIBC can coexist with genuine iron deficiency, and a low saturation calculated from a low TIBC can be misleadingly 'normal', so ferritin, CRP and sometimes the soluble transferrin receptor are used to sort it out.

Common causes

Inflammation and chronic disease
Infection, rheumatoid arthritis, inflammatory bowel disease, lupus, chronic kidney disease, heart failure, obesity and cancer raise interleukin-6 and hepcidin, lower transferrin synthesis and trap iron in macrophages. Ferritin is normal or high while serum iron and TIBC are both low.
Hereditary hemochromatosis
HFE mutations (most often C282Y homozygosity) remove the brake on gut iron absorption; iron accumulates over decades in the liver, pancreas, heart, joints and pituitary. TIBC is low-normal, saturation above 45 percent and ferritin rises progressively.
Transfusional and other secondary iron overload
Each unit of red cells delivers about 200 to 250 mg of iron with no route for excretion; people with thalassemia major, sickle cell disease on chronic transfusion or myelodysplasia accumulate iron rapidly. Long-term iron supplements without deficiency, and excessive dietary iron in some populations, do the same slowly.
Ineffective erythropoiesis
Thalassemia, myelodysplastic syndromes, sideroblastic anemia and B12 deficiency increase iron absorption through signals from the overactive marrow while red cells die before release; serum iron and ferritin rise and TIBC falls.
Chronic liver disease and cirrhosis
The liver makes transferrin; in cirrhosis, alcoholic liver disease, hepatitis C and advanced fatty liver disease production falls and injured hepatocytes release iron and ferritin, giving a high saturation that can mimic hemochromatosis.
Malnutrition and low protein intake
Transferrin falls within 1 to 2 weeks of inadequate protein and energy intake and is used alongside albumin and prealbumin to assess nutritional status; levels below 200 mg/dL are mild and below 100 mg/dL severe depletion. It recovers with refeeding.
Nephrotic syndrome and protein-losing enteropathy
Transferrin (molecular weight about 80 kDa) is lost in the urine when the kidney filter leaks protein, and into the gut in protein-losing bowel disease, lowering TIBC and sometimes causing iron deficiency at the same time.
Hypothyroidism and aging
Thyroid hormone stimulates transferrin synthesis, so untreated hypothyroidism lowers TIBC modestly; transferrin also declines gradually with age, so an older adult's TIBC runs somewhat lower.
Hereditary atransferrinemia
A very rare inherited absence of transferrin causes severe iron-deficiency anemia alongside tissue iron overload, because iron cannot reach the marrow but is still absorbed. TIBC is near zero.

Symptoms that can go with it

Often none; the low value is found when an iron panel is checked for anemia or fatigue
Tiredness and breathlessness from anemia of chronic disease, alongside the symptoms of the underlying condition
Joint pain, especially in the knuckles of the index and middle fingers, with iron overload
Fatigue, loss of libido or erectile dysfunction, and bronzed or grey skin in hemochromatosis
Right upper abdominal discomfort, raised liver enzymes or diabetes developing without the usual risk factors
Swelling of the legs or around the eyes and frothy urine in nephrotic syndrome
Weight loss, muscle wasting and low albumin in malnutrition or advanced liver disease

Read it alongside

Ferritin — the single best measure of iron stores when there is no inflammation; below 30 ng/mL confirms iron deficiency, above 300 (men) or 200 (women) raises the question of overload or inflammation.
Serum iron and transferrin saturation — saturation (iron ÷ TIBC × 100) below 20 percent fits deficiency or inflammation; above 45 percent fits overload and triggers HFE testing.
Hemoglobin, MCV and RDW — show whether the iron problem has reached the red cells: iron deficiency gives a low hemoglobin with small cells and a high RDW; anemia of inflammation gives normal-sized cells.
CRP — a raised CRP explains a low TIBC and a high ferritin and warns that ferritin up to about 100 ng/mL may still hide iron deficiency.
Reticulocyte count and reticulocyte hemoglobin — a low Ret-He (below 28 pg) shows the marrow is iron-starved even when ferritin is confusing; a reticulocyte rise 7 to 10 days into iron confirms the diagnosis.
Albumin and prealbumin — fall with transferrin in malnutrition, liver disease and nephrotic syndrome, pointing to a protein cause for a low TIBC.
Liver enzymes (ALT, AST, GGT) — raised in hemochromatosis and chronic liver disease, both of which lower TIBC and raise saturation.
Soluble transferrin receptor (sTfR) — rises in true iron deficiency but not in inflammation, so it separates the two when ferritin is 30 to 100 ng/mL and CRP is raised.

What usually happens next

If the pattern is iron deficiency, the questions are where the iron is going and why it is not being absorbed: menstrual history, diet, gut symptoms, aspirin or NSAID use, and a celiac antibody test. Men and post-menopausal women are usually referred for upper and lower gastrointestinal endoscopy to exclude a bleeding source, even if there are no gut symptoms.
Treatment of deficiency is iron, usually by mouth; expect a repeat CBC and ferritin at 4 weeks (hemoglobin should have risen by at least 1 g/dL) and continued treatment for about 3 months after hemoglobin normalises to refill stores, with TIBC drifting back down as ferritin recovers.
If the pattern is inflammation, the next step is to find and treat the inflammatory cause; iron tablets are not helpful unless ferritin is also below about 100 ng/mL, and intravenous iron is sometimes used in kidney disease, heart failure and inflammatory bowel disease when saturation is below 20 percent.
If the pattern is overload (saturation above 45 percent and raised ferritin on a fasting repeat), expect HFE genotyping, liver enzymes and, if ferritin is above 1,000 ng/mL, assessment of liver fibrosis; first-degree relatives of someone with hemochromatosis should also be tested.
Ask for the whole panel to be drawn fasting in the morning with any iron supplement held for 24 hours, since a recent tablet can push serum iron and saturation into the overload range for several hours.

Diet, lifestyle and natural levers with evidence

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

Iron-rich foods paired with vitamin C (for high TIBC from deficiency)

Strong evidence

Heme iron in red meat, poultry, fish and shellfish is absorbed at 15 to 35 percent whatever else is on the plate; non-heme iron in lentils, beans, tofu, fortified cereals, pumpkin seeds and dark greens is absorbed at 2 to 20 percent and is strongly meal-dependent. Classic isotope studies showed 25 to 100 mg of vitamin C with a meal raises non-heme iron absorption two- to fourfold, roughly the amount in a glass of orange juice or half a bell pepper. Adding vitamin C tablets to an iron supplement, by contrast, made no difference to the hemoglobin response in a 2020 randomised trial, so the lever is about meals, not pills. Diet maintains stores and corrects mild deficiency over months; established anemia usually needs a supplement too.

Check ferritin first: a low TIBC is not iron deficiency, and extra iron is harmful in hemochromatosis, thalassemia and some liver diseases.

Oral iron: dose and alternate-day timing (for confirmed deficiency)

Strong evidence

Oral ferrous salts raise hemoglobin by about 1 g/dL every 2 to 3 weeks and normalise TIBC and ferritin over 3 to 6 months. Stable-isotope randomised trials from Zurich showed that a single morning dose of 60 to 120 mg elemental iron every other day is absorbed about a third more efficiently per dose than daily dosing, because each dose raises hepcidin for 24 to 48 hours and blocks the next; follow-up trials in iron-deficient women found hemoglobin and ferritin gains comparable to daily dosing over 2 to 3 months with fewer gastrointestinal side effects. Doses above 100 mg a day add side effects without much extra absorption.

Common side effects are nausea, constipation and dark stools. Take 1 to 2 hours apart from tea, coffee, calcium, antacids and thyroid hormone. Iron tablets are a leading cause of poisoning in young children; store them out of reach. Do not supplement without a documented deficiency.

Timing iron away from tea, coffee and calcium

Moderate evidence

Single-meal absorption studies show that black tea taken with a meal cuts non-heme iron absorption by 60 to 90 percent and coffee by 40 to 60 percent, through polyphenols that bind iron in the gut; 300 to 600 mg of calcium from milk, cheese or a supplement roughly halves absorption of both heme and non-heme iron in the same meal, although the long-term effect is smaller than single-meal studies suggest. A 1 to 2 hour gap removes most of the inhibition, and vitamin C in the meal partly offsets it. For someone trying to bring a high TIBC down by refilling iron stores, this timing matters as much as what they eat.

Cooking in cast-iron cookware

Moderate evidence

Acidic, moist foods such as tomato sauce, chilli and stews pick up several milligrams of iron per serving from cast iron, and the amount increases with cooking time and acidity. In a randomised trial of Ethiopian children, meals cooked in iron pots raised hemoglobin about 1.3 g/dL more than meals from aluminium pots over 12 months, and a systematic review of trials found a positive effect on hemoglobin or iron status in most studies in low-income settings, although a trial of iron ingots in Cambodian cooking pots found no benefit. It is a useful maintenance measure where dietary iron is marginal rather than a treatment for anemia.

Avoid in hemochromatosis, thalassemia and other iron-overload conditions.

Lactoferrin as an alternative to ferrous salts

Preliminary evidence

Bovine lactoferrin, an iron-binding milk protein, has been compared with ferrous sulfate in several small randomised trials, mainly in pregnant women in Italy and Egypt. A meta-analysis of four trials found lactoferrin (100 to 250 mg once or twice daily) produced equal or slightly greater rises in hemoglobin and ferritin than ferrous sulfate over 4 to 8 weeks, with markedly fewer gastrointestinal side effects, possibly by lowering hepcidin. Trials are small and short, so it is an option to discuss when standard iron is not tolerated rather than a first choice.

Derived from cow's milk; avoid with a milk protein allergy. Evidence outside pregnancy is thin.

Adequate protein and energy intake (for low TIBC from malnutrition)

Preliminary evidence

Because transferrin has a half-life of about 8 to 10 days, it falls within 1 to 2 weeks of inadequate protein intake and recovers at a similar pace with refeeding; in hospital nutrition studies transferrin rose by 50 to 100 mg/dL over 2 to 3 weeks of adequate protein (about 1.2 to 1.5 g per kg of body weight a day) in depleted patients. This applies only when a low TIBC reflects malnutrition or recovery from illness, not when inflammation or iron overload is the cause.

When to see a clinician promptly

Iron deficiency (high TIBC, low ferritin) in a man or a post-menopausal woman, or in anyone with black or bloody stools, weight loss or a change in bowel habit: a bleeding source in the gut must be excluded.
A hemoglobin below 7 to 8 g/dL, or any anemia with chest pain, breathlessness at rest, fainting or a racing heart: possible severe anemia needing same-day care.
A transferrin saturation above 45 percent with a raised ferritin on a fasting repeat, particularly with joint pain, fatigue, raised liver enzymes, diabetes or a family history of hemochromatosis.
A low TIBC with a ferritin above 1,000 ng/mL, which raises the risk of liver damage from iron and needs specialist assessment.
Iron deficiency that has not responded after 4 weeks of oral iron (hemoglobin rise under 1 g/dL), which suggests ongoing bleeding, malabsorption or the wrong diagnosis.
Swelling of the legs or face with frothy urine, or jaundice, abdominal swelling and confusion, alongside a low TIBC: kidney or liver disease needs prompt evaluation.

Frequently asked questions

What is a normal TIBC level?

About 250 to 450 µg/dL (45 to 81 µmol/L) in adults, although laboratories set slightly different limits such as 240–450 or 262–474. Transferrin, the protein TIBC mostly measures, is normally about 200 to 360 mg/dL. Values are naturally higher in pregnancy and on estrogen-containing medication and somewhat lower in older adults.

What does a high TIBC mean?

Usually that you are short of iron. The liver makes more transferrin when stores are low, so TIBC climbs above about 400 to 450 µg/dL while serum iron, saturation and ferritin fall. Pregnancy and estrogen-containing contraceptives or hormone therapy also raise TIBC without any iron problem, which is why ferritin is checked alongside it. In adults who are not menstruating or pregnant, iron deficiency means looking for a source of blood loss or a cause of poor absorption.

What does a low TIBC mean?

Either that your body already has plenty of iron, as in hemochromatosis or after many transfusions, or that something is suppressing transferrin production: inflammation and chronic disease (the most common reason), liver disease, malnutrition or protein loss through the kidneys. Serum iron, saturation and ferritin separate these. Low TIBC with high iron and high ferritin suggests overload; low TIBC with low iron and high-normal ferritin suggests inflammation.

What is the difference between TIBC and ferritin?

Ferritin reflects how much iron is in storage; TIBC reflects how much transport capacity your liver is providing. They usually move in opposite directions: low ferritin with high TIBC means deficiency, high ferritin with low TIBC means overload or inflammation. Ferritin is the more sensitive and specific test for iron stores when there is no inflammation, but because it rises with any inflammation, TIBC, serum iron and saturation are needed to interpret a ferritin between about 30 and 100 ng/mL in someone who is unwell.

What is UIBC and how does it relate to TIBC?

UIBC is the unsaturated iron-binding capacity, the portion of transferrin not currently carrying iron: TIBC minus serum iron. Normal is roughly 150 to 375 µg/dL. Some laboratories measure UIBC directly and calculate TIBC from it. A high UIBC means many empty binding sites (iron deficiency); a low UIBC means most sites are full (iron overload).

Can TIBC be high without iron deficiency?

Yes. Pregnancy raises TIBC to 450 to 550 µg/dL through estrogen even when iron stores are adequate, and the combined pill and oral hormone replacement therapy raise it by 10 to 20 percent. Acute hepatitis can raise it briefly. In these situations ferritin is normal and serum iron is not markedly low. Conversely, TIBC can be normal despite iron deficiency when inflammation, liver disease or malnutrition is pulling it down at the same time.

Does a high TIBC mean I should take iron?

Only if ferritin confirms deficiency (generally below 30 ng/mL, or below 45 to 100 with inflammation) and the cause has been considered. In that case oral iron, usually 60 to 120 mg of elemental iron once daily or on alternate days, with a recheck at 4 weeks, is the standard approach, continued for about 3 months after hemoglobin normalises. If ferritin is normal, a high TIBC is more likely pregnancy or estrogen and iron is not needed. Do not start iron for a low TIBC.

Do I need to fast for a TIBC test?

TIBC itself changes slowly and is not much affected by food, but it is almost always drawn with serum iron to calculate transferrin saturation, and serum iron is highest in the morning, falls through the day and rises for several hours after an iron tablet or an iron-rich meal. For the most reliable panel, have blood taken in the morning after an overnight fast and hold iron supplements for 24 hours, unless your clinician says otherwise.

References

Iron tests. MedlinePlus, US National Library of Medicine (2023)View source
Iron deficiency anemia. Merck Manual Professional Version (2024)
Short MW, Domagalski JE. Iron deficiency anemia: evaluation and management. American Family Physician (2013)
Crownover BK, Covey CJ. Hereditary hemochromatosis. American Family Physician (2013)
Weiss G, Ganz T, Goodnough LT. Anemia of inflammation. Blood (2019)
Ko CW, Siddique SM, Patel A, et al.. AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia. Gastroenterology (2020)
Kowdley KV, Brown KE, Ahn J, Sundaram V. ACG clinical guideline: hereditary hemochromatosis. American Journal of Gastroenterology (2019)
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)
Cook JD, Monsen ER. The effect of vitamin C on iron absorption. American Journal of Clinical Nutrition (1977)
Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. British Journal of Nutrition (1999)
Li N, Zhao G, Wu W, et al.. The effect of vitamin C supplementation on hemoglobin in patients with iron deficiency anemia: a randomized clinical trial. JAMA Network Open (2020)
Iron fact sheet for health professionals. National Institutes of Health, Office of Dietary Supplements (2024)View source

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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.