Total iron binding capacity

Definition

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.

Alternative Names

TIBC; Anemia -TIBC

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
• 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: Males: 50 to 150 mcg/dL (8.95 to 26.85 micromol/L); Females: 35 to 145 mcg/dL (6.26 to 25.95 micromol/L)
• Total iron binding capacity (TIBC): Males: 171 to 505 mcg/dL (30.6 to 90.3 micromol/L); Females: 149 to 492 mcg/dL (26.7 to 88.0 micromol/L)
• Iron saturation: Males: 20% to 50%; Females: 15% to 45%

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

Camaschella C. Disorders of iron homeostasis: iron deficiency and overload. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 37.

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.

Means Jr RT. Approach to the anemias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 144.