Gastrin blood test (fasting)
Quick answer: A gastrin test measures gastrin, a hormone that makes the stomach release acid. Doctors order it to look for a rare gastrin-making tumour (Zollinger-Ellison syndrome), usually when ulcers are severe or keep coming back.
- SampleBlood
- TakesAbout 5 minutes
- Before the testFast overnight; tell your doctor about acid-reducing medicines, as they can raise gastrin and your doctor may advise on timing.
How the test is done
- 1You fast overnight, usually for about 12 hours
- 2Tell your doctor about acid-reducing medicines you take
- 3A needle draws blood from a vein
- 4The lab measures gastrin
What your results can mean
Reading your report
Normal ranges differ between labs and by age and sex, so discuss your result with your doctor.
If the result is outside the usual range
A high level can be seen with acid-reducing medicines, low stomach acid conditions such as atrophic gastritis, kidney disease, or, rarely, a gastrin-making tumour. Very high levels with high stomach acid point more to a tumour.
Who usually has this test
People with severe, repeated or unusual stomach ulcers, or ulcers with diarrhoea.
Risks and aftercare
Eat once the sample is taken; a small bruise may appear.
Names and options
Also called: serum gastrin
Listed by the hospital as
- GASTRIN (FASTING), SERUM
Questions about this test
Can acid-reducing medicines affect gastrin?
Yes. Proton pump inhibitors can raise gastrin a lot. Your doctor may advise on timing, but do not stop them without advice.
Why is fasting needed for a gastrin test?
Eating raises gastrin. A fasting sample gives a clearer result.
What is Zollinger-Ellison syndrome?
It is a rare condition in which a tumour makes too much gastrin, causing high stomach acid and severe ulcers.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.