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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

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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 is an autoimmune condition that can occur when the body's immune system targets its own tissues and develops antibodies directed against the parietal cells and/or intrinsic factor.

  • Parietal cells are specialized cells in the stomach that make acid to help in food digestion and also make intrinsic factor.
  • Intrinsic factor is required for the absorption of vitamin B12 from food.

During digestion, stomach acids produced by parietal cells release vitamin B12 from food, which binds to intrinsic factor to form a complex. The formation of this complex allows vitamin B12 to be absorbed in the small intestine. Among having functional roles in the brain and nervous system, vitamin B12 is important in the production of red blood cells (RBCs).

When the body’s immune system mistakenly targets its own tissues and develops antibodies directed against parietal cells and/or intrinsic factor, it can cause inflammation and progressively damage the parietal cells. This autoimmune condition, called autoimmune atrophic gastritis, can disrupt the production or function of intrinsic factor.

Without sufficient intrinsic factor, vitamin B12 goes largely unabsorbed, leading to vitamin B12 deficiency. Deficiency in vitamin B12 can result in megaloblastic anemia, characterized by the production of fewer but larger red blood cells (macrocytes). Vitamin B12 deficiency can also result in nerve-related signs and symptoms (neuropathy), such as numbness and tingling that start first in the hands and feet, muscle weakness, slow reflexes, loss of balance and unsteady walking. Other disorders can cause vitamin B12 deficiency and result in megaloblastic anemia. When it is due to a lack of intrinsic factor, it is called pernicious anemia. Besides anemia, a decrease in the numbers of neutrophils and platelets (neutropenia, thrombocytopenia) may also occur.

The tests for parietal cell and/or intrinsic factor antibodies may be used along 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.