Fasting gastric pH and its relationship to true hypochlorhydria in humans.

Abnormally low rates of gastric acid secretion (hypochlorhydria) are associated with bacterial overgrowth, enteric infection, and with hypergastrinemia and an increased risk of gastric neoplasms. In the present study, we evaluated the ability of fasting gastric juice pH measurements to detect true hypochlorhydria. True hypochlorhydria was defined as a peak acid output in response to a maximally effective stimulant of acid secretion that was below the lower limit of normal for 365 consecutive healthy subjects. In these healthy subjects, average basal pH was 2.16 +/- 0.09 in men and 2.79 +/- 0.18 in women. In 109 consecutive experiments in 28 subjects with true hypochlorhydria, fasting gastric pH averaged 7.44 +/- 0.11 in men and 7.65 +/- 0.33 in women. Fasting pH exceeded the upper 95% confidence limit of normal (5.09 in men and 6.81 in women) in 102 of the 109 experiments (94%). Thus, fasting pH measurement was a sensitive method for diagnosing bona fide hypochlorhydria.