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

OBJECTIVESTo 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. DESIGNPatients with suspected cobalamin deficiency and serum cobalamin < 200 μmol/l were investigated using upper gastrointestinal endoscopy, the Schilling test and serum tests for H K-ATPase antibodies, pepsinogen A, and H. pylori. SETTINGThe Department of Internal Medicine, Sahlgrenska University Hospital, Goteborg, Sweden. PATIENTSNinety seven consecutively referred patients. MAIN OUTCOME MEASURESSensitivity and specificity of assays for serum H K-ATPase antibodies, serum pepsinogen A, and the Schilling test RESULTSAssays 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. CONCLUSIONPepsinogen 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.