Serum antibodies to H+ K+-ATPase, serum pepsinogen A and Helicobacter pylori in relation to gastric mucosa morphology in patients with low or low-normal concentrations of serum cobalamins

OBJECTIVES: To compare the diagnostic performance of serum antibodies to H+,K+-ATPase (EC 3.6.1.36), serum pepsinogen A (EC 3.4.23.1) and the Schilling test in diagnosing chronic atrophic body gastritis; to study the interrelationships between H+,K+-ATPase antibodies, serology for Helicobacter pylori, and gastric morphology. DESIGN: Patients with suspected cobalamin deficiency and serum cobalamin < 200 micromol/l were investigated using upper gastrointestinal endoscopy, the Schilling test and serum tests for H+,K+-ATPase antibodies, pepsinogen A, and H. pylori. SETTING: The Department of Internal Medicine, Sahlgrenska University Hospital, Göteborg, Sweden. PATIENTS: Ninety seven consecutively referred patients. MAIN OUTCOME MEASURES: Sensitivity and specificity of assays for serum H+,K+-ATPase antibodies, serum pepsinogen A, and the Schilling test. RESULTS: Assays of serum antibodies to H+,K+-ATPase and of serum pepsinogen A displayed equal diagnostic sensitivity for atrophic gastritis (around 0.90 for the severe forms) and higher than that for the Schilling test (0.65). The diagnostic specificity for pepsinogen A (1.0) was higher than for H+,K+-ATPase antibodies (about 0.80). The prevalence of antral gastritis and positivity for H. pylori antibodies declined with the transition of body gastritis into severe atrophy, while the prevalence of H+,K+-ATPase antibodies increased. CONCLUSION: Pepsinogen A is preferable to serum H+,K+-ATPase antibodies in the diagnosis of gastric body mucosal atrophy. The formation of H+,K+-ATPase antibodies does not seem to be a primary event in the development of gastric body muscosal atrophy.