title: Reassessment of intrinsic factor and parietal cell autoantibodies in atrophic gastritis with respect to cobalamin deficiency.
abstract: OBJECTIVE
  Atrophic body gastritis (ABG) is an autoimmune condition eventually manifesting itself as pernicious anemia (PA). Parietal cell autoantibodies (PCAs) and intrinsic factor autoantibodies (IFAs) are considered characteristics of these conditions. Recent studies on IFA and PCA frequency with respect to cobalamin deficiency in biopsy-proven ABG patients are lacking. We addressed this issue using new enzyme-linked immunosorbent assay (ELISA)-based assays.
  
  
  METHODS
  Sera from 165 patients with histologically diagnosed ABG and 113 controls were tested for IFA and PCA using ELISA. A total of 81 ABG patients had cobalamin deficiency and macrocytic anemia (Group 1-PA), 36 had cobalamin deficiency without macrocytic anemia (Group 2), and 48 had normal cobalamin levels (Group 3).
  
  
  RESULTS
  IFAs were detected in 44/165 ABG patients (27% sensitivity) and in 0/113 controls (100% specificity). PCAs were detected in 134 ABG patients (81% sensitivity) and in 11 controls (90% specificity). In Group 1, IFAs showed 37% sensitivity and 100% specificity, whereas PCAs showed 81% sensitivity and 90% specificity. Combining IFA and PCA testing increased the sensitivity to 61% in all ABG patients and to 73% in Group 1, while maintaining 100% specificity.
  
  
  CONCLUSIONS
  IFAs are 100% specific for biopsy-proven ABG and occurred in 27% of patients. PCAs occurred in 81% of ABG patients and in 10% of controls. Combining IFA and PCA testing significantly increases their diagnostic performance for ABG and PA, yielding a 73% sensitivity for PA. The non-invasive combined PCA and IFA assessment may be useful in selecting patients at risk for autoimmune gastritis to be confirmed by gastroscopic-histologic examination.
authors.affiliation: Department of Digestive and Liver Disease, 2nd Medical School, University Sapienza, Rome 00189, Italy.
authors.forename: Edith
authors.initials: E
authors.lastname: Lahner
authors.forename: Gary L
authors.initials: GL
authors.lastname: Norman
authors.forename: Carola
authors.initials: C
authors.lastname: Severi
authors.forename: Susan
authors.initials: S
authors.lastname: Encabo
authors.forename: Zakera
authors.initials: Z
authors.lastname: Shums
authors.forename: Lucy
authors.initials: L
authors.lastname: Vannella
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Delle Fave
authors.forename: Bruno
authors.initials: B
authors.lastname: Annibale
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D005757:Gastritis, Atrophic / Q000097:blood* / Q000150:complications* / Q000175:diagnosis; D006801:Humans; D007437:Intrinsic Factor / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010295:Parietal Cells, Gastric / Q000276:immunology*; D014806:Vitamin B 12 Deficiency / Q000097:blood* / Q000150:complications*
chemical_list: D001323:Autoantibodies; D007437:Intrinsic Factor