Gastrin
Also known as: G-17, G-34, big gastrin, little gastrin, gastrin-17, gastrin-34, heptadecapeptide gastrin, GAST, pentagastrin (synthetic analog)
Gastrointestinal peptide hormone — cholecystokinin/gastrin family; acts via CCK2R (cholecystokinin B receptor)
What it is
Gastrin is a hormone naturally produced in the stomach that drives acid secretion and helps regulate digestion after meals. Clinicians measure it to diagnose conditions like Zollinger-Ellison syndrome and autoimmune gastritis, and researchers study it as a therapeutic target in gastric neuroendocrine tumors, Barrett's esophagus, and gastric cancer.
The scientific side
gastrin is a peptide hormone predominantly synthesized and secreted by antral G cells of the stomach in response to dietary protein, amino acids, gastric distension, and elevated intragastric pH. Its major biological actions are mediated through the cholecystokinin-2 receptor (CCK2R, also called CCKBR), a G protein-coupled receptor expressed on gastric parietal cells, enterochromaffin-like (ECL) cells, and various neoplastic tissues. In the canonical acid-secretion pathway, gastrin stimulates ECL cells to release histamine, which in turn activates parietal cell H2 receptors to drive hydrochloric acid secretion. This three-way interaction between acetylcholine, gastrin, and histamine constitutes the principal regulatory axis for meal-stimulated gastric acidification established over a century of physiological research. Gastrin also exerts trophic effects on fundic oxyntic mucosa, promoting cell proliferation and mucosal growth via CCK2R-mediated signaling cascades including ERK, PI3K/Akt, and YAP pathways. Chronic hypergastrinemia — arising from proton pump inhibitor use, autoimmune atrophic gastritis, or gastrinoma — leads to ECL-cell hyperplasia and, in predisposed individuals, type 1 gastric neuroendocrine tumors. The gastrin/CCK2R signaling axis also participates in gastric carcinogenesis: CCK2R activation upregulates matrix metalloproteinase-2 and VEGF, promoting invasion and metastasis in gastric cancer models, while CCKBR knockdown reduces gastric cancer cell proliferation. Conversely, recent single-cell and mouse model work demonstrates that gastrin can act as a tumor suppressor by blocking symmetric division of CCK2R-positive stem cells in the gastric corpus, and that hypogastrinemia — as seen in autoimmune gastritis — paradoxically activates a vagal-cholinergic reflex driving CCK2R-positive progenitor expansion and preneoplastic progression. Beyond the gastrointestinal tract, gastrin regulates renal sodium excretion by activating CCKBR on renal tubular cells, a pathway modulated by dietary sodium and PPAR-alpha signaling. Large-scale UK Biobank proteogenomic analysis has further associated elevated circulating gastrin with risk across 152 common diseases spanning cardiovascular, autoimmune, and metabolic domains, positioning gastrin as a systemic multi-organ risk indicator rather than a purely digestive hormone.
Class: Gastrointestinal peptide hormone — cholecystokinin/gastrin family; acts via CCK2R (cholecystokinin B receptor)
Administration & storage
- Administration
- Intravenous infusion for radiolabeled CCK2R-targeting minigastrin analogs ([177Lu]Lu-DOTA-MGS5[68Ga]Ga-DOTA-MGS5) in nuclear medicine settingsSubcutaneous injection for pentagastrin diagnostic stimulation testing (now largely obsolete)Oral administration for CCK2R antagonist netazepide (investigational; 25–100 mg capsules)
- Storage
- Serum samples for gastrin measurement should be collected in EDTA or serum separator tubes, placed on ice, centrifuged within 30 minutes, and stored at -20°C if not assayed same day; freeze-thaw cycles degrade gastrin. Radiolabeled minigastrin analogs must be stored per radiopharmaceutical protocols with radiation shielding and used within validated shelf-life windows. Netazepide (investigational oral agent) stored at room temperature per standard pharmaceutical conditions.
- Cautions
- Serum gastrin interpretation requires knowledge of concurrent PPI or H2-blocker use, as these agents cause physiological hypergastrinemia that can mimic pathological elevations and confound ZES diagnosis,Radiolabeled CCK2R-targeting minigastrin analogs carry radiation exposure risks; dosimetry assessment required before [177Lu] therapeutic administration,Netazepide (CCK2R antagonist) may cause rebound acid hypersecretion upon abrupt discontinuation due to upregulation of parietal cell sensitivity; taper may be warranted,Pentagastrin stimulation testing (now obsolete in most markets) was associated with nausea, flushing, abdominal cramping, and transient hypotension,Long-term PPI-induced hypergastrinemia raises theoretical ECL-cell hyperplasia risk; periodic endoscopic surveillance recommended in patients on PPI therapy for >5 years, particularly those with underlying atrophic gastritis
Legal & regulatory status
Gastrin itself is not approved as a therapeutic drug in the United States. Pentagastrin, a synthetic gastrin analog, was historically used as a diagnostic agent for gastric acid secretion testing but is no longer…
Gastrin is a naturally occurring endogenous peptide hormone and is not listed on the WADA Prohibited List as of the 2024 Prohibited List publication. Synthetic gastrin analogs or gastrin secretagogues used to…
Gastrin is not approved as a therapeutic agent in Canada. Serum gastrin measurement is used as a diagnostic biomarker in standard clinical practice for acid hypersecretory states. Drugs targeting the gastrin/CCK2…
What it's studied for
- Diagnostic biomarker for Zollinger-Ellison syndrome (ZES) and gastrinoma Human observational
- Biomarker for autoimmune atrophic gastritis and monitoring hypergastrinemia from proton pump inhibitor use Human observational
- CCK2R-targeted theranostics (radiolabeled minigastrin analogs) for medullary thyroid cancer and neuroendocrine tumors Translational / Early Clinical
- Type 1 gastric neuroendocrine tumor (gNET) regression with CCK2R antagonist netazepide Human RCT
- Barrett's esophagus — evaluation of gastrin/CCK2R antagonism to reduce dysplasia risk Human RCT
- Gastric cancer — gastrin/CCK2R signaling as a therapeutic target and prognostic factor Preclinical (Animal)
- Colorectal cancer and Barrett's esophagus — CCK2R expression and gastrin as diagnostic/therapeutic targets Mixed
- Renal sodium regulation — gastrin as a natriuretic hormone Mechanistic only
Safety signals
- ECL-cell hyperplasia and type 1 gastric neuroendocrine tumor development with chronic hypergastrinemia
- Gastric acid hypersecretion and peptic ulceration in Zollinger-Ellison syndrome
- Tumor-promoting effects via CCK2R in gastric cancer — gastrin/CCK2R axis contributes to proliferation, invasion, and metastasis
- Multi-systemic disease associations of elevated gastrin — positive associations with 152 common diseases including cardiovascular, autoimmune, and metabolic conditions in UK Biobank proteogenomic analysis
- Hypergastrinemia from PPI therapy — long-term PPI use causes physiological gastrin elevation (typically 2- to 4-fold above baseline), associated with ECL-cell changes and theoretical NET risk
- Gastrin loss (hypogastrinemia) paradoxically promotes preneoplastic progression in autoimmune gastritis — via vagal cholinergic reflex and CCK2R+ stem cell expansion
- Radiation exposure from [177Lu]Lu-labeled minigastrin analogs used in CCK2R-targeted radionuclide therapy
All studies (4)
Frequently asked
What does a high gastrin level mean?
Elevated fasting serum gastrin can result from several causes. The most common is taking proton pump inhibitors (PPIs) or H2 blockers, which suppress acid production and remove the normal feedback signal that keeps gastrin in check. Other causes include autoimmune atrophic gastritis (loss of acid-producing cells), Helicobacter pylori infection, renal failure, and — less commonly but most seriously — a gastrin-secreting tumor called a gastrinoma (Zollinger-Ellison syndrome). A gastrin level above 1,000 pg/mL in a patient not on acid-suppressing drugs is highly suspicious for ZES and warrants specialist gastroenterology evaluation. Mild elevations (100–500 pg/mL) on PPI therapy are usually physiological and expected. Your clinician will interpret the result in the context of your medications and clinical picture.
Is gastrin used as a treatment or therapy?
Gastrin itself is not approved or used as a therapeutic drug. It is primarily studied and measured as a hormone to diagnose digestive disorders. However, drugs that block the gastrin receptor (CCK2R) — such as the investigational agent netazepide — are being studied to treat gastric neuroendocrine tumors and Barrett's esophagus. Additionally, radioactively labeled peptides that mimic gastrin are being tested in clinical trials to image and treat rare cancers that overexpress the gastrin receptor, such as medullary thyroid cancer. None of these therapies are yet approved for routine clinical use.
Can long-term proton pump inhibitor use cause problems through gastrin?
Long-term PPI use consistently elevates gastrin levels because the drugs reduce stomach acid, which removes the acid-mediated feedback that normally keeps gastrin suppressed. This sustained hypergastrinemia stimulates the growth of enterochromaffin-like (ECL) cells in the stomach lining. In the general population this is considered low risk, but in patients with pre-existing autoimmune gastritis or significant mucosal atrophy, prolonged ECL-cell stimulation could theoretically increase the risk of type 1 gastric neuroendocrine tumors. Current guidelines suggest that patients on long-term PPIs for more than 5 years who have underlying atrophic gastritis may benefit from periodic endoscopic surveillance. The absolute risk remains low, but it is an area of active research and an important reason for not using PPIs without a clear indication.
What is the difference between gastrin-17 and gastrin-34?
Both are natural forms of the gastrin hormone, differing by chain length. Gastrin-17 (G-17) is a 17-amino-acid peptide and is the predominant form secreted by antral G cells after a meal; it is the most potent stimulator of gastric acid secretion and the form measured in the GastroPanel biomarker assay for gastric mucosal health. Gastrin-34 (G-34, 'big gastrin') is produced in larger amounts in the fasting state and has a longer plasma half-life, though it is less biologically potent per mole than G-17. Both bind the same receptor (CCK2R) and both are elevated in hypergastrinemic states such as ZES and autoimmune atrophic gastritis. Commercial gastrin assays may measure total gastrin (all molecular forms) or be specific for G-17, so interpreting results requires knowing which assay was used.
Does gastrin have any role in cancer?
Yes, gastrin has a complex relationship with several cancers. In gastric cancer, activation of the CCK2R (gastrin receptor) by gastrin promotes tumor cell proliferation, invasion, and blood vessel formation; overexpression of CCK2R is found in many gastric cancers and is associated with poorer prognosis. In autoimmune gastritis, chronic hypergastrinemia drives ECL-cell hyperplasia and can eventually lead to type 1 gastric neuroendocrine tumors (a generally low-grade cancer). In colorectal cancer, CCK2R is also overexpressed. Conversely, new research shows that in certain contexts gastrin can actually suppress symmetric stem-cell division in the stomach, suggesting it has both tumor-promoting and tumor-protective roles depending on cell type and context. Gastrin's role in cancer is an active area of research, with clinical trials testing CCK2R-targeted radionuclide therapies and gastrin receptor antagonists in various tumors.