Health Encyclopedia

Total iron binding capacity

Definition

Total iron binding capacity (TIBC) is a blood test that shows if there is too much or too little iron in the blood. Iron is carried in the blood attached to the protein transferrin. This test helps measure the ability of a protein called transferrin to carry iron in the blood.

Alternative Names

TIBC

How the test is performed

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

How to prepare for the test

You should not eat or drink for 8 hours before the test.

Make sure your doctor knows about all the medications you are taking. Some medicines can interfere with test results.

Drugs that can raise TIBC include fluorides and birth control pills.
Drugs that can lower TIBC include ACTH and chloramphenicol.

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 sensation. Afterward, there may be some throbbing.

Why the test is performed

This test is usually done when the health care provider suspects low iron (deficiency) as a cause of anemia.

Normal Values

Iron: 60-170 mcg/dL
TIBC: 240-450 mcg/dL
Transferrin saturation: 20-50%

Note: mcg/dl = micrograms per deciliter

What abnormal results mean

TIBC is usually higher-than-normal when the body's iron stores are low. Higher-than-normal TIBC may mean:

Iron deficiency anemia
Pregnancy (late)

Lower-than-normal TIBC may mean:

Cirrhosis
Hemolytic anemia
Hypoproteinemia
Inflammation
Liver disease
Malnutrition
Pernicious anemia
Sickle cell anemia

What the risks are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient 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 light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

References

Ginder G. Microcytic and hypochromic anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 163.

Review Date:2/13/2009
Reviewed By:David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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