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?

You may need this test if your healthcare provider 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 healthcare provider might order a vitamin B₁₂ test or a folate level 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 healthcare provider might order an anti-parietal cell antibody test, which measures the presence of certain antibodies in the stomach.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

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 is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

Injected vitamin B₁₂ could affect results. If you have had an injection of the vitamin, your healthcare provider 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. Be sure your healthcare provider 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.