Gastrin

Hormone produced by G cells in the stomach that regulates gastric acid secretion. Elevated levels are associated with gastrinoma (Zollinger-Ellison syndrome), recurrent peptic ulcers, pernicious anemia, and achlorhydria. Requires overnight fasting (12-14 hours). Normal adult levels: 0-115 pg/mL. Levels >1000 pg/mL with gastric acid hypersecretion suggest gastrinoma.