Usefulness of anti-gastric parietal cell and anti-intrinsic factor antibodies in the study of vitamin B12 deficiency associated with autoimmune gastritis and pernicious anemia

Autoimmune gastritis (AIG) is a progressive inflammatory condition of the oxyntic mucosa, characterised by gastric parietal cell destruction, loss of intrinsic factor, and malabsorption of vitamin B-12 (cobalamin), iron and other micronutrients; conditioning progress to a state of megaloblastic anemia known as pernicious anemia (PA). The aim of this study was to determine vitamin B-12 deficiency due to malabsorption utilizing anti -parietal cell (APCA) and anti -intrinsic factor (IFA) antibodies detection. 2050 patient serum samples were analised by chemiluminescent immunoassay for vitamin B-12. A total of 2.8% of them were tested for APCA by indirect immunofluorescence and for IFA by enzyme immunoessay. Vitamin B-12 deficiency (<200 ng/mL) was 13.1%. Regarding antibody detection: 2 APCA/IFA double positives, 17 APCA simple positives and 4 IFA simple positives were found. APCA and/or IFA positive samples had total vitamin B-12 values <200 ng/mL. Chronic gastritis confirmed by biopsy was diagnosed in 5 patients with positive ACPG antibodies. All 6 IFA positive patients were diagnosed with PA, while 2 of them also received histopatologic confirmation. APCA and/or IFA confirmation allowed for the classification of patients with suspicion of AIG as possible candidates for histologic examination and application of appropriate therapeutic schemes. Importance of laboratory testing is to be noted; as part of a strategy that enables early diagnosis and adequate endoscopic surveillance, to avoid manifestations related to iron and vitamin B(12 )deficiency and the complications of advanced disease.