TIBC; Anemia -TIBC Total iron binding capacity (TIBC) is a blood test to see if you have too much or too little iron in your blood. Iron moves through the blood attached to a protein called transferrin. This test helps your health care provider know how well that protein can carry iron in your blood. Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
You should not eat or drink for 8 hours before the test.
Certain medicines may affect the result of this test. Your provider will tell you if you need to stop taking any medicines. Do not stop any medicine before talking to your provider.
Medicines that can affect the test result include:
- Adrenocorticotropic hormone (ACTH)
- Birth control pills
- Chloramphenicol
- Fluorides
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
Your provider may recommend this test if:
- You have signs or symptoms of anemia due to low iron
- Other lab tests suggest you have anemia due to low iron levels
Normal Results
Normal value range is:
- Iron: 60 to 170 micrograms per deciliter (mcg/dL) or 10.74 to 30.43 micromoles per liter (micromol/L)
- TIBC: 240 to 450 mcg/dL or 42.96 to 80.55 micromol/L
- Transferrin saturation: 20% to 50%
The numbers above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
TIBC is usually higher than normal when the body's iron supplies are low. This can occur with:
- Iron deficiency anemia
- Pregnancy (late)
Lower-than-normal TIBC may mean:
- Anemia due to red blood cells being destroyed too quickly (hemolytic anemia)
- Lower-than-normal level of protein in the blood (hypoproteinemia)
- Inflammation
- Liver disease, such as cirrhosis
- Malnutrition
- Decrease in red blood cells from the intestines not properly absorbing vitamin B12 (pernicious anemia)
- Sickle cell anemia
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Multiple punctures to locate veins
- Hematoma (blood buildup under the skin)
- Infection (a slight risk any time the skin is broken)
References
Brittenham GM. Disorders of iron homeostasis: iron deficiency and overload. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 36.
Markell M, Siddiqi HA. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 27.
Version Info
Last reviewed on: 1/25/2022
Reviewed by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Does this test have other names?
Total iron-binding capacity, TIBC, transferrin saturation
What is this test?
This test measures the amount of the protein transferrin in your blood.
Your liver makes transferrin. When your body's stores of iron run low, your liver makes more transferrin to get more iron into your blood.
Iron plays many important roles in your body, including helping your red blood cells carry oxygen to the cells in your body. Nearly all the iron in your body is normally attached to transferrin.
Normally, your body carefully keeps track of your iron level and tries to keep it from rising too high or falling too low.
This test can give your healthcare provider more information about health issues like anemia that are affecting your body's iron supply.
Why do I need this test?
You may need this test if your healthcare provider suspects that you have a certain type of anemia. In general, anemia means you have a low number of red blood cells. One type of anemia is iron-deficiency anemia. If you have this type, you don't have enough iron to correctly make hemoglobin. Hemoglobin is the substance that helps your red blood cells carry oxygen.
Symptoms of anemia can include:
Extreme tiredness or weakness
Loss of stamina
Pale skin color
Dizziness
Irritability
Headaches
Shortness of breath and fast heartbeat during physical activity
Less common symptoms include abnormal cravings, brittle nails, and restless leg syndrome.
Anemia usually happens because of blood loss or because you aren't absorbing enough iron from your food. Pregnant women are also at higher risk of developing this problem.
What other tests might I have along with this test?
Your healthcare provider may also order other tests, including:
Complete blood count (CBC)
Tests to measure how much iron is in your blood
Measurement of ferritin, a protein that holds most of your body's iron reserves
Stool tests
What do my test results mean?
Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
Results are given in milligrams per deciliter (mg/dL). The normal range for transferrin is 215 to 380 mg/dl. If you have a higher amount, you may have iron-deficiency anemia. If you have a lower level, you may have another problem, such as liver disease or hemolytic anemia.
Transferrin may also be measured using a value called total iron-binding capacity (TIBC). Results are given in micrograms per deciliter (mcg/dL). Normal values are 250 to 450 mcg/dL. A higher level means that you may have iron-deficiency anemia.
Another measurement, called transferrin saturation, checks how many places on your transferrin that can hold iron are actually doing so. Normal values are 15% to 50%. In severe cases of iron-deficiency and anemia, this number may fall below 10%.
Many other health conditions can cause high or low levels of transferrin. The results of these tests, and other tests, can help your healthcare provider determine the cause of your symptoms.
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Aspirin, antibiotics, and birth control pills can affect your results.
How do I get ready for this test?
You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.