To help diagnose pernicious anemia, the most common cause of vitamin B12 deficiency
Parietal Cell Antibody
As part of an investigation, when you have anemia and/or neuropathy that may be due to a vitamin B12 deficiency; when you have red blood cells that are much larger than normal (macrocytic)
A blood sample drawn from a vein in your arm
None
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How is it used?
A parietal cell antibody test may be used along with or following an intrinsic factor antibody test to help determine the cause of a vitamin B12 deficiency and to help confirm a diagnosis of pernicious anemia.
It is usually used as a follow-up test after other laboratory tests, such as a vitamin B12 test, a methylmalonic acid test, or a complete blood count (CBC) with a blood smear examination, establish that a person has a vitamin B12 deficiency and associated megaloblastic anemia and/or neuropathy.
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When is it ordered?
The parietal cell antibody test is not a frequently ordered test because it is not as specific as the intrinsic factor antibody test. It may be ordered when a person has signs and symptoms that suggest a vitamin B12 deficiency and when pernicious anemia is suspected. Signs and symptoms may include:
- Larger than normal red blood cells (RBCs); these are often detected before the other signs and symptoms emerge, found, for example, with a CBC during routine testing for a health examination.
- Pale complexion
- Weakness, fatigue
- Numbness and tingling in the feet and/or hands that may be due to neuropathy
These findings usually prompt vitamin B12 and folate testing and may lead to methylmalonic acid testing (an early indicator of vitamin B12 deficiency) and homocysteine testing.
An intrinsic factor antibody test and parietal cell antibody test may be ordered as follow-up tests when a person has a decreased vitamin B12 level and increased methylmalonic acid and homocysteine levels.
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What does the test result mean?
The results of this test are often taken into consideration with the results of other laboratory tests to help make a diagnosis.
A decreased vitamin B12 level and/or increased methylmalonic acid and homocysteine levels as well as a positive test result for intrinsic factor antibodies and/or parietal cell antibodies means that it is likely that the person tested has pernicious anemia.
A negative test result does not necessarily mean that a person does not have pernicious anemia. At least 10% of those affected will not have parietal cell antibodies.
Parietal cell antibodies are not as specific as intrinsic factor antibodies. About 90% of those with pernicious anemia will have parietal cell antibodies, but they may also be found in:
- Up to 50% of people with gastritis (inflammation of the stomach lining)
- Up to 30% of people with inflammation of the thyroid gland (thyroiditis)
- A variety of other conditions and autoimmune disorders
- A small percentage of the general population
The parietal cell antibody test is not used to diagnose or monitor these conditions.
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Is there anything else I should know?
Vitamin B12-associated anemia may take several years to develop as a normal person typically has large stores of B12 in reserve. Symptoms tend to emerge only when these stores become depleted.
Recent evidence indicates that people with type 1 diabetes may have an increase in the risk of developing parietal cell antibodies.
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Can I prevent, decrease, or get rid of parietal cell antibodies?
No, they are produced by your immune system and do not respond to preventive measures or lifestyle changes. The associated vitamin B12 deficiency, however, can usually be successfully treated and managed.
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If I can't absorb vitamin B12, how can I get enough?
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Should everyone have a parietal cell antibody test?
No. It is not intended as a general screening test. It is usually only performed when a person has a demonstrated vitamin B12 deficiency to help determine the cause.
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How long will it take for results?
It depends on the laboratory performing the test. This test requires specialized equipment and is not offered by every laboratory. In some cases, your blood sample will need to be sent to a reference laboratory and it may take a few days before results are available.