Intragastric pH continuously monitored in health and in gastric diseases: chronobiologic assessment.

: Some gastric diseases clinically show ultradian, circadian, and circannual periodicities. We continuously monitored, during a single 24-hr span, with a fully electronic, solid-state portable recorder, endoluminal gastric pH in five healthy subjects, in some patients with gastric diseases including duodenal ulcer and gastric cancer, and in high-risk persons prone to develop duodenal ulcer and gastric cancer. The daily schedule and the timing of standardized meals for each subject were strictly verified. All stored data (300 time points/subject) were decoded, read, and analyzed by an inferential statistical method to estimate the rhythm parameters. The intragastric dense pH samples showed highly significant circadian and ultradian (8-hr) rhythms in all investigated subjects, but rhythm parameters differed in pre- and in overt pathology.