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Parietal Cell Antibody

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Also known as: Gastric Parietal Cell Antibody; Anti-parietal Cell Antibody; Anti-GPA; AGPA; APCA
Formal name: Gastric Parietal Cell Antibody, IgG

The Test Sample

What is being tested?

Parietal cell antibodies are autoantibodies, proteins produced by the immune system that mistakenly target a type of specialized cells that line the stomach wall. This test detects these antibodies in the blood to help diagnose pernicious anemia.

Pernicious anemia can occur when the body's immune system targets its own tissues and develops antibodies directed against the parietal cells and/or the intrinsic factor. Intrinsic factor is a protein produced by the parietal cells and is required for the absorption of vitamin B12 from food. During digestion, stomach acids (also produced by parietal cells) release vitamin B12 from food, and intrinsic factor ultimately binds to the vitamin B12 and allows it to be absorbed at a specific segment of the small intestine. Among other functions, vitamin B12 is important in the production of red blood cells (RBCs). Without sufficient intrinsic factor, vitamin B12 goes largely unabsorbed and the body cannot produce enough normal RBCs, leading to anemia. Besides anemia, decrease in the numbers of neutrophils and platelets (neutropenia, thrombocytopenia) may also occur.

Parietal cells antibodies and other autoantibodies called intrinsic factor antibodies can disrupt intrinsic factor production or function. Both of these antibodies can lead to a decrease in the amount of intrinsic factor available, causing deficiency in vitamin B12.

Deficiency in vitamin B12 can lead to megaloblastic anemia, which is characterized by the production of fewer but larger RBCs called macrocytes. Several different factors can cause a B12 deficiency and result in megaloblastic anemia. When it is due to a lack of intrinsic factor, it is called pernicious anemia.

The tests for parietal cell and/or intrinsic factor antibodies may be used with several other tests, such as complete blood count (CBC) and blood smear, to help diagnose pernicious anemia.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.