Spontaneous and persisting decrease in maximal acid output.

A spontaneous decrease in maximal acid output was observed in three control subjects and in seven patients with duodenal ulcer. The decreased output was due to a decrease in volume and to a lower concentration in six subjects and to a decrease in volume in four subjects. In some cases the decrease in output occurred within a period of weeks. Patients with a pronounced decrease remained asymptomatic for a prolonged period.