A patient seated in the chair before a blood draw
In person

Iron + TIBC

Your blood iron, carrying capacity, and saturation, from one draw.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
A standard blood draw at the lab.
Preparation
Morning draw is best
Before 10 a.m. is preferred. Iron runs highest in the morning.
Results
1 to 2 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

This test measures serum iron and total iron binding capacity (TIBC), then calculates saturation. Iron levels change through the day, so the lab prefers a morning draw after an overnight fast. Together, the three help a healthcare provider see whether iron is running low, high, or affected by inflammation.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

Adults with questions about low iron or iron overload, heavy periods, or a past ferritin result often use this test, read with ferritin. Commonly related symptoms include:

Body

  • Tiredness or weakness
  • Breathless with activity

Skin

  • Pale skin

Head

  • Lightheadedness

Reproductive

  • Heavy periods

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your results show how much iron is moving in your blood and how full its carrier protein is, which can help a healthcare provider see whether your iron is running low or high.

Iron
This measures the iron circulating in your blood, most of it carried by a protein called transferrin. Iron is needed to make hemoglobin. The level varies through the day and after meals or supplements, which is why a morning, fasting sample is preferred and why it is read with TIBC and ferritin.
Why it’s measured: Iron in your blood right now, usually checked in the morning after fasting.
Total iron-binding capacity (TIBC)
TIBC measures how much iron your blood could carry if all the binding sites on transferrin were filled. When iron stores run low, the body tends to make more transferrin, so TIBC often rises. It helps a provider tell iron deficiency from other causes of a low iron result.
Why it’s measured: Shows how much iron your blood could carry, which helps a provider interpret low iron.
Transferrin saturation (calculated)
Transferrin saturation is the percentage of iron-binding sites in your blood that are filled with iron. The lab calculates it from your iron and TIBC results. Together with ferritin, it helps a provider look at whether iron is low or whether too much iron may be building up.
Why it’s measured: The share of iron-carrying capacity in use, from iron and TIBC.

How it works

  1. Step 1

    Order online

    Check out here. A licensed clinician in your state reviews your order and sends it to the lab.

  2. Step 2

    Visit a lab

    Bring a photo ID to any of 2,000+ lab locations. Before 10 a.m. is preferred. Iron runs highest in the morning. Nothing is due at the lab.

  3. Step 3

    Get your results

    Results post to your account, usually in 1 to 2 days, each number next to the lab’s reference range.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

Iron and TIBC are reported in micrograms per deciliter (mcg/dL), and saturation as a percentage, each next to the lab’s reference range.

  • Each marker next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

Iron results are read together and with ferritin. A healthcare provider can explain what yours mean and whether anything else is needed.

Ferritin, serum iron, or iron and TIBC?

Three iron tests, three different views of the same system.

Iron and TIBC

Serum iron plus how much more iron your blood could carry.

Shows
Iron, carrying capacity, and saturation
Timing
Morning draw after an overnight fast preferred
Keep in mind
Helps a clinician tell low iron stores from the effects of inflammation

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

Iron levels change through the day and tend to be higher in the morning, so the lab prefers a morning draw. Eating beforehand can add fat to the blood, which can interfere with the measurement.

That is why the prep for this test is a draw before 10 a.m. after an overnight fast. Water is fine.

If you take insulin or other diabetes medicines, ask your prescriber how to fast safely before your visit.

Most iron in the blood travels on a carrier protein called transferrin. TIBC reflects how much iron transferrin could carry if it were full. Saturation is your iron divided by TIBC, the share of that capacity in use.

Saturation tends to be low in iron deficiency and high in iron storage diseases.

Iron and TIBC show how iron is moving in your blood at the time of the draw, not how much is stored. Recent meals and the time of day can shift the numbers. Ferritin adds the view of stored iron, and a healthcare provider reads them together before drawing any conclusion.

No. This test is not for emergencies. If you have chest pain, severe shortness of breath, fainting, heavy bleeding, or black or bloody stools, get emergency care right away rather than waiting for a lab visit or a result.

Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.