Anti-Gastric Parietal Cells

What is the role of gastric parietal cells?

Parietal cells, located in the stomach wall, perform two functions essential to digestion and nutrient absorption. They produce the hydrochloric acid needed to digest proteins and protect against certain ingested pathogens. They also secrete intrinsic factor, a glycoprotein essential for the absorption of vitamin B12 in the small intestine. When anti-parietal cell antibodies progressively destroy these cells, both functions are compromised.

When is this test prescribed?

• Macrocytic or megaloblastic anemia of unknown cause
• Documented vitamin B12 deficiency, especially in a person with no obvious dietary factors
• Clinical suspicion of autoimmune atrophic gastritis or pernicious anemia
• Expanded autoimmune workup in a person with another autoimmune disease (Hashimoto's thyroiditis, type 1 diabetes, vitiligo, etc.).
• Peripheral neuropathy or unexplained neurological damage associated with B12 deficiency
• Chronic gastritis with achlorhydria documented by gastroscopy

How to interpret the result?

What is the sensitivity and specificity of this test?

Anti-parietal cell antibodies have a relatively high sensitivity for autoimmune atrophic gastritis, but their specificity is limited. They can be detected in healthy people, particularly after the age of 60, with no associated disease. For this reason, this test should never be interpreted on its own: it should always be considered as part of an overall clinical and biological picture.

What other tests are often combined?

• Anti-intrinsic factor antibodies: more specific for pernicious anemia, but less sensitive
• Determination of serum vitamin B12 and folates
• Blood count with blood smear (to detect macrocytes and megaloblasts)
• Serum gastrin: often elevated in atrophic gastritis with achlorhydria
• Pepsinogen I and II: indirect markers of fundic mucosal atrophy
• Thyroid tests and anti-thyroid antibodies: frequently associated with gastric autoimmune diseases

What is pernicious anemia?

Pernicious anemia is the long-term consequence of autoimmune destruction of gastric parietal cells. The absence of intrinsic factor prevents intestinal absorption of vitamin B12, gradually leading to profound deficiency. This deficiency manifests itself as macrocytic anemia (large, insufficient red blood cells), but also as neurological damage that may include paresthesias, ataxia or cognitive disorders. Once diagnosed, B12 deficiency is corrected with supplements, the route of administration being determined by the physician according to the degree of impairment of intestinal absorption.

Are there any false positives to be aware of?

Yes, anti-parietal cell antibodies can be detected in the absence of any documented gastric autoimmune disease in a number of situations: elderly population over 60 (up to 10 % positivity without associated pathology), active Helicobacter pylori infection, autoimmune thyroiditis, type 1 diabetes, and other systemic autoimmune diseases. This reality underlines the importance of a contextualized interpretation by a physician.

Consult at Clinique Omicron

Clinique Omicron's healthcare professionals, at our Quebec locations, can prescribe and interpret this test as part of a complete biological work-up. If you present with persistent fatigue, numbness, anemia or documented vitamin B12 deficiency, a medical consultation will help guide investigations and establish an appropriate follow-up plan.

The content of this page is provided for informational purposes only and is not intended to replace the advice of a qualified healthcare professional. Consult a physician for any symptoms, questions or decisions you may have regarding your health.