The short answer
TIBC measures how much iron your blood’s carriers could hold. It goes up when you’re short of iron, and Labcorp flags anything over 450 µg/dL.1
Check your result
Type the number from your report. It stays on this page.
- Low Under 250
- In range 250 to 450
- High 451 or more
Enter your result to see what it means and what to do next.
Got a result from another lab? Ask Picardo about it. The app explains your results, and a physician can follow up.
Cutoffs are Labcorp’s.1 TIBC rarely gives an answer on its own, so read it with your iron and saturation. The bar isn’t to scale.
Low: look beyond iron
Your blood has fewer iron carriers than usual. Inflammation and liver disease such as cirrhosis can cause it, as can low protein levels from poor nutrition or kidney disease.1 In hemochromatosis, TIBC is often slightly low, with a very high saturation.1 A low TIBC can also push saturation up without any extra iron, which can be mistaken for hemochromatosis.4
Not urgent on its own.
- 1 Look at your saturation. If it’s 45% or more, ask about testing for hemochromatosis.3
- 2 Check your liver tests and protein levels with a metabolic panel.1
- 3 If you’ve been ill recently, recheck once you’re well.1
In the lab’s range
Your iron-carrying capacity is typical. Ferritin is the more sensitive test for low iron, so a normal TIBC doesn’t rule it out.1
Nothing to worry about.
- 1 Check the iron and saturation on the same report.1
- 2 If you’re tired or have heavy periods, check ferritin.1
High: check for low iron
TIBC rises when you’re short of iron. It also rises in pregnancy and with birth control pills. On the pill, saturation stays normal.1 If your iron and saturation are low too, that pattern indicates iron deficiency.1
Not urgent. Worth following up in the next few weeks.
- 1 Check ferritin. US hematologists suggest counting 30 ng/mL or under as iron deficiency, and up to 50 if you have symptoms of low iron or a risk factor such as heavy periods, a vegan or vegetarian diet or donating blood.2
- 2 Check your hemoglobin to see whether you’re anemic.
- 3 If you take the pill and your saturation is normal, that may be the whole explanation.1
What is a normal TIBC level?
Labcorp’s range is 250 to 450 µg/dL.1 Low iron, high TIBC and low saturation together indicate iron deficiency. Without all three, this test alone can’t prove it:1
Low: look beyond iron
Your blood has fewer iron carriers than usual. Inflammation and liver disease such as cirrhosis can cause it, as can low protein levels from poor nutrition or kidney disease.1 In hemochromatosis, TIBC is often slightly low, with a very high saturation.1 A low TIBC can also push saturation up without any extra iron, which can be mistaken for hemochromatosis.4
Not urgent on its own.
In the lab’s range
Your iron-carrying capacity is typical. Ferritin is the more sensitive test for low iron, so a normal TIBC doesn’t rule it out.1
Nothing to worry about.
High: check for low iron
TIBC rises when you’re short of iron. It also rises in pregnancy and with birth control pills. On the pill, saturation stays normal.1 If your iron and saturation are low too, that pattern indicates iron deficiency.1
Not urgent. Worth following up in the next few weeks.
- 1 Check ferritin. US hematologists suggest counting 30 ng/mL or under as iron deficiency, and up to 50 if you have symptoms of low iron or a risk factor such as heavy periods, a vegan or vegetarian diet or donating blood.2
- 2 Check your hemoglobin to see whether you’re anemic.
- 3 If you take the pill and your saturation is normal, that may be the whole explanation.1
What is TIBC?
Think of transferrin as a fleet of buses that carries iron around your body. TIBC counts the seats and serum iron counts the passengers. Transferrin saturation is the share of seats that are taken.
Iron travels in your blood on a protein called transferrin, which your liver makes.3 TIBC, short for total iron-binding capacity, is how much iron your transferrin could carry if every spot were filled. It’s your serum iron plus the empty spots, which your report lists as UIBC.3
Your report also gives transferrin saturation: your serum iron as a share of your TIBC.5
How to read iron, TIBC and saturation together
| Iron | TIBC | Saturation | |
|---|---|---|---|
| Iron deficiency | Low | High | Low |
| Anemia of long-term illness | Low | Low or normal | Low or normal |
| Hemochromatosis | High | Slightly low | Very high |
| Red blood cells breaking down | High | Normal or low | High |
Patterns from Labcorp’s notes on the test. Used together, these results usually tell iron deficiency apart from the anemia of long-term illness.1
TIBC on its own rarely answers the question. European liver specialists use it only to work out saturation, which they read alongside ferritin.4 And ferritin is a more sensitive test than serum iron or TIBC, for both low and high iron.1
What causes high or low TIBC?
High TIBC comes from:1
- Iron deficiency
- Pregnancy
- Birth control pills
Low TIBC comes from:1
- Inflammation and infection
- Liver disease, such as cirrhosis
- Low protein, from poor nutrition or kidney disease that leaks protein (nephrotic syndrome)
- Hemochromatosis, which lowers it slightly
Who should get a TIBC test?
TIBC comes with serum iron and saturation in one test. It’s useful if:
- You’re anemic, especially with small red blood cells (a low MCV).1
- Your ferritin is high, to check your saturation for hemochromatosis.3
- A close relative has hemochromatosis.3
- You may not be eating enough. TIBC also reflects your nutrition.1
If you only want to know whether you’re low on iron, start with ferritin. It’s the more sensitive test.1
How to get a TIBC test, and what it costs
It comes from the iron and TIBC test, which costs $6.00 through Picardo.
Iron and TIBC test
The test this number comes from.
- Results in 2 to 3 days, in the app
- Physician follow-up if you want one
- Free Labcorp draw, or $75 at home
- No other fees. HSA and FSA eligible.
It’s also part of the Base Core Annual – Men, Base Core Annual – Women and Celiac / GI panels, if you’d rather test more at once.
Already have a result? Ask Picardo about itQuestions people ask
What is UIBC on my report?
Unsaturated iron-binding capacity, the empty spots on your iron carriers. Add it to your serum iron and you get TIBC.3 A low UIBC, like a high saturation, can be a sign of hemochromatosis.3
Is TIBC the same as transferrin?
Close. Transferrin is the protein that carries iron, and TIBC measures how much iron it can hold.3 Some labs measure transferrin directly and work out saturation from it, which is more reliable.5
Often checked alongside
Test details
- Labcorp test
- Iron and Total Iron-binding Capacity (TIBC), 001321
- LOINC
- 2500-7
- Sample
- Blood
- Fasting
- Labcorp doesn’t require it.1 But US hematologists advise having iron tests drawn after 5 to 9 hours without food, multivitamins or iron pills, because a recent meal or pill can skew the result.2
- Typical lab range
- 250 to 450 µg/dL1
- Units
- µg/dL, which Labcorp prints as ug/dL. For µmol/L, multiply by 0.179.
Sources
- 1 Labcorp. Iron and total iron-binding capacity (TIBC), test 001321, and sample report. Labcorp test menu. Accessed October 28, 2026. www.labcorp.com/tests/001321/iron-and-total-iron-binding-capacity-tibc
- 2 Powers JM, Lim MY, Achebe MO, et al. American Society of Hematology 2026 guidelines for diagnosis of iron deficiency. Blood Adv. 2026;10(21):7353–7374. doi.org/10.1182/bloodadvances.2025015950
- 3 Kowdley KV, Brown KE, Ahn J, Sundaram V. ACG clinical guideline: hereditary hemochromatosis. Am J Gastroenterol. 2019;114(8):1202–1218. doi.org/10.14309/ajg.0000000000000315
- 4 European Association for the Study of the Liver. EASL Clinical Practice Guidelines on haemochromatosis. J Hepatol. 2022;77(2):479–502. doi.org/10.1016/j.jhep.2022.03.033
- 5 Girelli D, Busti F, Brissot P, et al. Hemochromatosis classification: update and recommendations by the BIOIRON Society. Blood. 2022;139(20):3018–3029. doi.org/10.1182/blood.2021011338
Updated 4 Nov 2026.
This is general health information, not medical advice: talk to your clinician about your results and before changing any treatment.