Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.
The first hormone ever described (1902) — the discovery that founded endocrinology.
Part of the Metabolic & GLP-1 peptides cluster
Overview
Secretin is a 27-amino-acid hormone released from duodenal S-cells in response to stomach acid entering the small intestine. Discovered by Bayliss and Starling in 1902, it was the first substance ever called a hormone and remains a landmark in the history of endocrinology.
Source & context
Biological / chemical source: Duodenal S-cells
Primary research or clinical context: Endogenous hormone; used diagnostically (e.g., pancreatic function and gastrinoma testing)
Historic significance
Secretin's discovery demonstrated that a chemical messenger carried in the blood — not just nerves — could coordinate organs. That insight launched the entire concept of hormones. It gives its name to the 'secretin family' of related peptides that includes glucagon, GLP-1 and GIP.
Physiology and diagnostic use
When acidic chyme reaches the duodenum, secretin signals the pancreas to release bicarbonate-rich fluid, neutralizing the acid and protecting the intestinal lining. Its predictable action is exploited in diagnostic stimulation tests. Coverage here is educational and describes physiology rather than any therapeutic protocol.
Sequence
One-letter sequence commonly cited for Secretin (educational; isoforms and modifications may differ):
HSDGTFTSELSRLREGARLQRLLQGLV
Residues plotted ~100° apart around an α-helix — clustering of one color reveals an amphipathic face.
Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Secretin (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- IUPHAR/BPS source snapshot · 2026-10-01
- PubChem molecular record · 2026-10-01
- Molecular formula
- C130H219N43O42
- Average reference mass
- ≈ 3,056.4
- Status
- Approved medicine in at least one jurisdiction (IUPHAR record)
- PubChem CID: 16129665
- IUPHAR ligand: 3643
- ChEMBL: CHEMBL1201488
- CAS RN: 108153-74-8
- UNII: 88C55N56UU
Chemistry values: PubChem, IUPHAR/BPS Guide to Pharmacology · fetched 2026-10-01.
Clinical development snapshot
ClinicalTrials.gov lists 53 registered studies with “Secretin” as an intervention (snapshot 2026-09-06). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT06276764 | The LINFU® U.S. Registry in Patients With IPMN (Intraductal Papillary Mucinous Neoplasm of the Pancreas) | — | enrolling by invitation | 2026-08-06 |
| NCT07285863 | A Study Of Effect Of Secretin For In Injection (Chirostim) On Pancreatic Fluid Composition In Healthy Subjects | Phase 4 | recruiting | 2026-07-07 |
| NCT07651748 | Secretin in Ex-situ Liver Perfusion | Phase 2 | enrolling by invitation | 2026-06-16 |
| NCT05659147 | Imaging Biomarkers of Pancreatic Function and Disease | Phase 4 | enrolling by invitation | 2026-03-18 |
| NCT05235867 | Secretin in Refeeding | — | recruiting | 2026-02-12 |
| NCT03099850 | Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies | — | recruiting | 2025-10-14 |
Secretin — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Secretin (source record; form not independently established)Average reference mass: 3,056.4 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
FAQ about Secretin
What is Secretin?+
Secretin is a 27-amino-acid hormone released from duodenal S-cells in response to stomach acid entering the small intestine. Discovered by Bayliss and Starling in 1902, it was the first substance ever called a hormone and remains a landmark in the history of endocrinology.
What Canadian product status is recorded for Secretin?+
Canadian product status for Secretin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Secretin?+
Secretin is commonly described as approximately 27 amino acids (Hormone).
Related peptides
References & further reading
- 1.Long et al. (2007). Secretin-receptor and secretin-receptor-variant expression in gastrinomas: correlation with clinical and tumoral features and secretin and calcium provocative test results. J Clin Endocrinol Metab
- 2.Chey et al. (2003). Secretin, 100 years later. J Gastroenterol
- 3.Chey et al. (2014). Secretin: historical perspective and current status. Pancreas
- 4.Tam et al. (2014). Molecular evolution of GPCRs: Secretin/secretin receptors. J Mol Endocrinol
- 5.Bartlett et al. (2025). Secretin targets interstitial cells of Cajal to regulate intestinal contractions. EMBO Rep
- 6.Siu et al. (2006). Signaling mechanisms of secretin receptor. Regul Pept
- 7.Afroze et al. (2013). The physiological roles of secretin and its receptor. Ann Transl Med
- 8.Wu et al. (2020). Functional Role of the Secretin/Secretin Receptor Signaling During Cholestatic Liver Injury. Hepatology
- 9.PubChem — compound summary for Secretin (CID 16129665)
- 10.Wikipedia — Secretin