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.
How the Test is Performed
A blood sample is needed.
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.
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
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.
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)
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)
- Liver disease, such as cirrhosis
- Decrease in red blood cells from the intestines not properly absorbing vitamin B12 (pernicious anemia)
- Sickle cell anemia
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
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.
Chernecky CC, Berger BJ. Iron (Fe) and total iron-binding capacity (TIBC)/transferrin – serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier; 2013:691-692.