Intragastric acidity and circadian rhythm.

Most patients with peptic ulcers or gastroesophageal reflex disease develop subjective symptoms of epigastralgia and retrosternal pain during the period of time from the middle of the night to the early dawn (nocturnal pain). Such pain often disappears before breakfast. Disturbed circadian rhythm of gastric acid secretion may have a close relationship with the onset and aggravation of acid-related diseases. On the other hand, Helicobacter pylori has been considered to be an etiological agent of duodenal ulcer, and H. pylori eradication has been conducted in patients with gastritis and peptic ulcers. However, such eradication therapy sometimes results in the onset or deterioration of gastroesophageal reflux diseases. In this context, the question of whether the circadian rhythm of gastric acid secretion varies in accordance with the presence or absence of H. pylori infection is of interest. In the present study, we examined the fluctuation in intragastric acidity via a portable pH meter in 10 H. pylori-positive and 10 H. pylori-negative subjects. As a result, a significant difference in the circadian rhythmicity was observed between the H. pylori-negative and the H. pylori-positive group, with mean values for each parameter of 28.1 and 13.3 for amplitude, 22.7 and 12.4 for the midline-estimating statistic of rhythm (MESOR), and 324.0 and 321.0 for acrophase, respectively (P < 0.001). In both H. pylori-positive and negative groups, a tendency was observed toward an increase in intragastric acidity during the time period from the middle of the night to the early dawn, and toward a decrease in intragastric acidity during the early morning. In the H. pylori-positive group, the values for intragastric acidity over time were lower, and the degree of amplitude was smaller as compared to the H. pylori-negative group. Further, H. pylori-positive individuals were at a more advanced stage of the disease.