GAST and gastritis: Therefore, based on our data, normal serum gastrin and the absence of IFA have a fair negative predictive value for autoimmune lesion of the mucosa of the stomach, as demonstrated by correlating the biopsy profile with the laboratory results in the 39 subjects of Groups 3 and 4; they tested positive for PCA only (notably, at very low values in those with gastritis due to Hp), but showed no lesions of gastric epithelium.