A drug used to help diagnose gastrinomas (tumors that cause too much gastric acid to be made) and other problems with the pancreas. It is also used to increase secretions from the pancreas and to help identify a duct called the ampulla of Vater. Synthetic human secretin is a form of secretin that is made in the laboratory. Secretin causes the pancreas, liver, and stomach to release substances that help digest food. Also called ChiRhoStim and secretin human.