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Iron and Total Iron-Binding Capacity

Do these tests have other names?

Iron (Fe), serum iron, TIBC

What are these tests?

The serum iron test measure the amount of iron in your blood. The total iron-binding capacity (TIBC) test looks at how well the iron moves through your body.

Iron is an important mineral that your body needs to stay healthy. Your body uses iron to make hemoglobin, the protein in your red blood cells that carries oxygen throughout your body. If you don't have enough iron, you may not have enough hemoglobin. This condition is called iron deficiency anemia.

Iron in your body is carried, or bound, mainly to a protein made by your liver called transferrin. The TIBC test is based on certain proteins, including transferrin, found in the blood. Your transferrin levels are almost always measured along with iron and TIBC.

Why do I need these tests?

You may need these tests if your doctor thinks your iron level is too low or too high. Not having enough iron in your diet is the most common cause of anemia and the most common type of diet deficiency in the U.S. Your doctor may do this test to look at your diet, nutrition, liver, or other conditions that cause iron to be low, such as increased blood loss or pregnancy.

Symptoms of iron deficiency include:

  • Being tired and feeling weak

  • Getting frequent infections

  • Feeling cold all the time

  • Having swelling in the tongue

  • Struggling to keep up at school or work

  • In children, having delayed mental development

Symptoms of too much iron can include:

  • Feeling tired and weak

  • Joint pain

  • Abdominal pain

What other tests might I have along with these tests?

Iron, TIBC, and transferrin blood tests are almost always done together. Other blood tests that may also be done include measuring your hemoglobin; your percent of red blood cells, or hematocrit; and all the cells in your blood, called a complete blood count.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Normal results of iron testing may be different for men, women, and children. Iron and TIBC are measured in micrograms per deciliter (mcg/dL). Normal results for iron are:

  • 65 to 175 mcg/dL for men

  • 50 to 170 mcg/dL for women

  • 50 to 120 mcg/dL for children

Normal results for TIBC are 250 to 450 mcg/dL for men and women.

Some common conditions that may cause the amount of iron in your blood to be too low include:

  • Iron deficiency anemia

  • Other types of anemia

  • Blood loss over time

  • Long-standing infections or diseases

  • Last three months of pregnancy

Some common conditions that may cause the amount of iron in your blood to be too high include:

  • Conditions that cause red blood cells to die, called hemolytic anemia

  • Iron or lead poisoning

  • Iron overload, such as from hemochromatosis

  • Many blood transfusions

  • Liver damage

Your doctor will look at your iron level in conjunction with the TIBC, transferrin, and possibly other tests to better understand what the results mean.

How are these tests done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Do these tests pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Many medications can affect the results of these blood tests. Some common drugs that may affect your results include alcohol, birth control pills, antibiotics, aspirin, estrogen, and testosterone. Women who are having their menstrual period may have decreased iron.

How do I get ready for these tests?

You may be asked to have these blood tests in the morning after fasting overnight. Normally, iron levels are closest to normal in the morning and get lower as the day goes on. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.