Gastrin is a peptide hormone produced primarily by G-cells in the stomach lining in response to food, particularly protein. Its main function is to stimulate the secretion of hydrochloric acid by parietal cells in the stomach, which is essential for protein digestion and killing ingested bacteria.
Elevated gastrin levels (hypergastrinaemia) can result from conditions such as Zollinger-Ellison syndrome — caused by a gastrin-secreting tumour — atrophic gastritis, or long-term use of proton pump inhibitors (PPIs). Testing gastrin is useful when investigating unexplained peptic ulcers, chronic diarrhoea, or high acid secretion that doesn't respond to standard treatment.
FAQs
Why do PPIs raise gastrin levels?
PPIs suppress acid production in the stomach. Normally, stomach acid inhibits gastrin release via a feedback loop. When PPIs block acid production, this feedback is removed and gastrin rises. This is a physiological response to the medication, not a disease, and levels return to normal when PPIs are stopped.
What is Zollinger-Ellison syndrome?
Zollinger-Ellison syndrome is caused by a gastrin-secreting neuroendocrine tumour (gastrinoma), usually in the pancreas or duodenum. Excess gastrin drives massive acid hypersecretion, causing severe recurrent peptic ulcers, often in unusual locations, and chronic diarrhoea. It can occur sporadically or as part of MEN-1 syndrome.
Should I stop PPIs before a gastrin test?
Yes. PPIs significantly raise gastrin and must be stopped for at least 1-2 weeks before testing for accurate results. This should only be done after discussing the risks with your doctor, as stopping PPIs abruptly can cause rebound acid hypersecretion.
Can gastrin be tested while fasting?
Yes — in fact, fasting for at least 8-12 hours is required for a reliable gastrin measurement, as food (particularly protein) stimulates gastrin release and will elevate results. The test should be collected in the fasted state.
