What does gastrin do?

Acid feedback loop: Gastrin is a hormone that responds to the amount of stomach acid produced--not enough acid causes gastrin levels to rise to stimulate acid production. Gastrin is suppressed when acid levels are adequate in normal patients. However, in those with hypersecretory states like zollinger-ellison syndrome, gastrin is continually produced in high concentration resulting in excess acid, diarrhea, ulcers.