FDA-approved
Hormones & metabolism
Secretin
Secretin is the first hormone ever discovered and an FDA-approved diagnostic agent. Learn how it tests pancreatic function and what the evidence shows.
- Reviewed by
- William Maish, MD MBA MPH, Clinical Product Lead
- Published
- October 5, 2026
- Last updated
- October 5, 2026
Key takeaway
Secretin (sold as ChiRhoStim) is a gastrointestinal hormone used as a diagnostic agent to stimulate the pancreas and measure how well it secretes. It was the very first substance ever called a "hormone," discovered in 1902, and today its synthetic form helps evaluate pancreatic function and detect gastrinoma. The human secretin product has been FDA-approved in the U.S. since 2004 and is given by injection during a diagnostic test.
At a glance
| What it is | A 27-amino-acid gastrointestinal hormone used as a diagnostic stimulant |
| Approved for | Assessing pancreatic exocrine function, diagnosing gastrinoma, and aiding duct identification during ERCP |
| Key fact | Secretin-stimulated imaging detects pancreatic duct abnormalities more sensitively than imaging alone |
| Route | Intravenous injection |
| Evidence strength | FDA approved |
What is secretin?
Secretin is a 27-amino-acid hormone normally released by the small intestine to signal the pancreas to secrete a bicarbonate-rich fluid that neutralizes stomach acid. The FDA-approved product, ChiRhoStim, is synthetic human secretin used not as a treatment but as a diagnostic agent that provokes a measurable pancreatic or gastric response. An earlier synthetic porcine secretin product has since been discontinued in favor of the human form.
The history of secretin
Secretin holds a unique place in medical history: it was the first hormone ever identified. In 1902, the physiologists William Bayliss and Ernest Starling showed that a substance released from the intestinal lining traveled through the blood to stimulate the pancreas, and Starling later coined the word "hormone" to describe such chemical messengers. Secretin therefore marks the beginning of endocrinology as a field, though its modern clinical role is diagnostic rather than therapeutic.
How does secretin work?
Secretin binds secretin receptors on the duct and acinar cells of the pancreas, stimulating secretion of a watery, bicarbonate-rich fluid. In a diagnostic test, giving secretin and then sampling or imaging the pancreatic output shows how well the gland can respond, which helps evaluate suspected exocrine pancreatic dysfunction. Secretin also stimulates gastrin release from the abnormal cells of a gastrinoma, producing a characteristic paradoxical rise in gastrin that helps confirm that tumor.
Because the test depends on the measured response, secretin is given as a single intravenous dose under controlled conditions. In clinical studies, secretin-enhanced imaging detected pancreatic duct abnormalities with higher sensitivity1 than imaging without stimulation.
Is it FDA-approved?
Yes. Synthetic human secretin (ChiRhoStim) was approved2 by the FDA in 2004 for these diagnostic uses:
| Diagnostic use | What secretin does |
| Diagnosis of exocrine pancreatic dysfunction | Stimulates pancreatic secretions |
| Diagnosis of gastrinoma | Stimulates gastrin secretion |
| Endoscopic retrograde cholangiopancreatography (ERCP) | Helps identify the pancreatic ducts |
What is secretin prescribed for?
Secretin is used as a diagnostic aid in three settings: evaluating pancreatic exocrine function, provoking a gastrin response to help diagnose gastrinoma, and facilitating duct visualization during ERCP. It is administered by a clinician as part of a specific test, not taken on an ongoing basis.
What are the side effects?
According to the prescribing information, the most common side effects of a single diagnostic dose are:
- Nausea
- Vomiting
- Flushing
- Upset stomach
More for hormones & metabolism
Sources: FDA prescribing information for ChiRhoStim; a study of secretin-stimulated pancreatic imaging (Sherman et al., Gastroenterology, 2014, DOI: 10.1053/j.gastro.2014.05.0351), indexed on PubMed; historical accounts of the Bayliss and Starling discovery of secretin. This document is educational and does not constitute medical advice.