Circadian acidity pattern in prepyloric ulcers: a comparison with normal subjects and duodenal ulcer patients

We used continuous 24-h pH monitoring to compare the circadian intragastric acidity of 36 patients with prepyloric ulcers (PPU) with that of 101 normal subjects (NS) and that of 206 patients with duodenal ulcer (DU). The ulcer crater was endoscopically ascertained in all cases, and PPU were located within an area up to 2 cm proximal to the pylorus. The pH curve pertaining to DU patients ran below that of NS during most of the circadian period, whereas the pH profile of PPU patients was higher than that of NS, and this was particularly true during the evening and the night. The acidity of PPU patients was significantly lower (p < 0.01) than that of NS during the night only, whereas it was lower (p < 0.05-0.001) than that of DU patients during each time interval analysed (24 h, nighttime, and daytime). Our findings show that the gastric acidity of PPU patients differs greatly from that of DU patients, since it is lower throughout the whole 24-h period, and particularly during the night. Thus these two entities are pathophysiologically different with regard to the acidity pattern and should be considered two distinct subgroups of peptic ulcer disease instead of being incorporated, as usually happens, in the clinical group 'duodenal ulcer disease'.