A TIBC (total iron-binding capacity) test is one of a few tests healthcare providers use to diagnose iron-related conditions, like anemia and hemochromatosis. They often compare the results to iron and ferritin blood test results.
A TIBC (total iron-binding capacity) test is a blood test that measures your blood’s ability (capacity) to attach (bind) to iron and carry it throughout your body. Healthcare providers use it to help diagnose iron-deficiency anemia and other iron metabolism conditions.
More specifically, a TIBC test shows the amount of transferrin in your blood. Transferrin is a protein your liver makes that regulates the absorption of iron into your blood.
Your body needs iron to make healthy red blood cells. Red blood cells carry oxygen from your lungs to the rest of your body. Iron is also important for healthy muscles, bone marrow and organ function.
TIBC and ferritin are related tests, but they’re distinct.
A ferritin test measures the level of ferritin — a protein that stores iron inside your cells. While a TIBC test measures how your body transports iron via transferrin, a ferritin test measures how much iron your body stores. Ferritin is a better marker to assess iron deficiency.
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Healthcare providers mainly order TIBC tests to diagnose conditions related to issues with iron. You could have too little iron in your body (iron-deficiency anemia) or too much (hemochromatosis).
A TIBC test is often part of an iron panel, which may also include the following tests:
Providers may also use TIBC tests to monitor iron-related conditions.
A healthcare provider called a phlebotomist usually performs blood draws. They send the sample to a lab where a medical laboratory scientist prepares the samples and performs the test on machines known as analyzers.
Your healthcare provider may ask you to fast (not eat or drink anything except for water) and avoid iron supplements for 12 hours before your test. If you have any questions about how to prepare, talk to your provider.
You can expect the following during a blood test or blood draw:
The entire procedure usually takes less than five minutes.
After a healthcare provider has collected your blood sample, they’ll send it to a laboratory for testing. Once the test results are back, your healthcare provider will share the results with you.
Blood tests are a very common and essential part of medical testing and screening. There’s very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.
In most cases, you should have your TIBC test results within one or two days, though it could take longer.
Laboratories often have different reference ranges for normal TIBC results. When you get your blood test results back, there will be information that states what that lab’s normal reference range is.
Generally, the normal TIBC range is 240 micrograms per deciliter (mcg/dL) to 450 mcg/dL.
It’s important to know that providers typically combine the results of TIBC and other tests, like blood iron and ferritin tests, to make diagnoses.
If you have a low TIBC level and a high blood iron level, it could mean you have hemochromatosis (iron overload). Low TIBC and low iron can be a sign of certain conditions, like:
Having low ferritin levels and high TIBC levels typically means you have iron-deficiency anemia, the most common form of anemia. It happens when your body doesn’t have enough iron to make hemoglobin, a substance in your red blood cell that allows them to carry oxygen throughout your body.
If your TBC test results are abnormal, it doesn’t necessarily mean that you have a medical condition. The following factors can affect your results:
If you have an abnormal result, your healthcare provider will discuss it with you. They’ll consider several factors before making a diagnosis. They may order additional tests to do so.
A note from Cleveland Clinic
Seeing an abnormal test result can be stressful. Know that having an abnormal TIBC result doesn’t necessarily mean you have a condition. Approximately 1 in 20 healthy people will have results outside of the normal range. Your healthcare provider will go over the results with you and together you’ll decide on the next steps. The good news is that most conditions that cause too little or too much iron in your body are treatable.
Last reviewed by a Cleveland Clinic medical professional on 05/11/2023.
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