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Intrinsic Factor Antibody

Does this test have other names?

IF antibody; intrinsic factor antibody level; intrinsic factor blocking antibody measurement; antibody level, intrinsic factor

What is this test?

This is a blood test for pernicious anemia, which is caused by a deficiency of vitamin B12. The disease used to be life-threatening, but today it can be treated with vitamin B12 shots or pills.

To get enough vitamin B12, your body needs a protein called intrinsic factor (IF). This protein is made by the lining of your stomach. It allows you to absorb vitamin B12 from the food you eat. Your body needs B12 to make healthy red blood cells. If you don't get enough B12, your red blood cells won't divide properly and will be too large, making it hard for them to squeeze out of the bone marrow. This can lead to anemia, or a lack of red blood cells. Without enough B12, your nervous and digestive systems also won't work properly.

The body produces antibodies to attack what it believes to be foreign substances. If your body sees IF as a foreign invader and makes antibodies against it, IF will be destroyed and cannot help your body absorb vitamin B12

Why do I need this test?

Your doctor might order this test if he or she suspects you have pernicious anemia or a vitamin B12 deficiency. Signs of anemia include:

  • Paleness

  • Tiredness

  • Weakness

  • Neuropathy, or tingling and numbness in the hands and feet; a "pins and needles" feeling

What other tests might I have along with this test?

As part of your diagnosis for pernicious anemia, your doctor might order a vitamin B12 test to measure the amount of the vitamin in your blood.

He or she might also order a Schilling test, a three-part procedure that can distinguish between pernicious anemia and other conditions with similar symptoms.

To help confirm the diagnosis, your doctor might order an anti-parietal cell antibody test, which measures the presence of certain antibodies in the stomach. 

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.

Test results that are negative for the presence of IF antibody are considered normal. But it's possible to have pernicious anemia in spite of this negative test result.

How is this test done?

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

Does this test 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?

Injected vitamin B12 could affect results. If you have had an injection of the vitamin, your doctor will probably ask you to wait for up to two weeks before testing.

How do I get ready for this test?

You don't need to prepare for this test.