From the Guidelines
Antiparietal cell antibody reactivity is a significant indicator of autoimmune gastritis, and patients testing positive should undergo further evaluation, including checks for anemia, vitamin B12 levels, and possibly gastric endoscopy, as recommended by the 2021 expert review in Gastroenterology 1. When antiparietal cell antibodies are detected, it suggests an autoimmune response targeting the parietal cells in the stomach, which can lead to conditions like pernicious anemia and autoimmune gastritis.
- Key considerations in the management of patients with antiparietal cell antibody reactivity include:
- Evaluating for anemia due to vitamin B12 and iron deficiencies, as suggested in the 2021 expert review 1
- Assessing vitamin B12 levels to determine the need for supplementation
- Possibly conducting a gastric endoscopy to evaluate the stomach lining for atrophy or other abnormalities
- Monitoring for gastric cancer risk with periodic endoscopic surveillance every 3-5 years in cases of autoimmune gastritis
- The presence of these antibodies can lead to decreased acid production and reduced vitamin B12 absorption due to their effect on the hydrogen/potassium ATPase pump or intrinsic factor in parietal cells.
- Given the association of antiparietal cell antibody reactivity with other autoimmune disorders, such as thyroid disease or type 1 diabetes, screening for these conditions may also be warranted in affected patients, as part of a comprehensive management approach 1.
From the Research
Antiparietal Cell Antibody Reactive
- Antiparietal cell antibodies (APCA) are a diagnostic tool for autoimmune atrophic gastritis (AAG) and pernicious anemia (PA) 2
- APCA target the H+/K+ ATP-ase, with the alpha subunit being the major antigen 2
- The presence of APCA is not sufficient for diagnosis, as they can also be found in individuals with other diseases, such as type 1 diabetes, autoimmune thyroid diseases, vitiligo, and celiac disease 2
- APCA can be detected by immunofluorescence, enzyme-linked immunosorbent assay, and radioimmunoprecipitation assay (RIA), with RIA being the most accurate method 2
Clinical Significance
- APCA are found in 85-90% of patients with PA, but are also present in 7.8-19.5% of the general healthy adult population 2
- The presence of APCA is associated with an increased risk of gastric carcinoma and neuroendocrine tumors 3
- Early detection of AIG through a proactive case-finding strategy, micronutrient supplementation, and endoscopic surveillance is crucial for management 3
Relationship with Vitamin B12 Deficiency
- APCA are often found in patients with severe vitamin B12 deficiency, with one study showing that 57% of patients with severe vitamin B12 deficiency were positive for APCA 4
- Vitamin B12 deficiency can lead to hemolytic anemia, which is a rare manifestation of the condition 5
- The presence of APCA and intrinsic factor blocking antibodies (IFBA) can indicate autoimmune atrophic gastritis, which may develop into pernicious anemia 4