A gastrin test measures the level of the
hormone gastrin in the blood. Gastrin is produced by
cells, called G cells, in the stomach lining. When food enters the stomach, G
cells trigger the release of gastrin in the blood. As blood levels of gastrin
rise, the stomach releases acid (gastric acid) that helps break down and digest
food. When enough gastric acid has been produced by the stomach, gastrin levels
in the blood drop.
Gastrin also has minor effects on the
intestines. Gastrin helps the pancreas produce
enzymes for digestion and helps the liver produce
bile. It also stimulates the intestines to help move
food through the
digestive tract .
Sometimes a test for
gastrin is done after eating a high-protein diet or after receiving an
injection of the digestive hormone secretin into a vein. This is called an
intravenous secretin test.
Why It Is Done
A gastrin test may be done to:
How To Prepare
Before having the gastrin test:
- Do not drink alcohol for 24 hours before the
- Do not eat for 12 hours before the test.
- Do not eat or drink anything with caffeine, such as coffee, for 12 hours before the test.
- Do not
chew gum or smoke cigarettes for 4 hours before the test.
- You can
drink as much water as you want up to 1 hour before the test.
Many medicines can change the results of this test.
Be sure to tell your doctor about all the nonprescription and prescription
medicines you take, especially acid-reducing medicines, such as Pepcid,
Prilosec, Rolaids, Tums, or Zantac. You may need to stop taking some medicines before this
Stress can affect gastrin levels, so you may be asked to rest quietly for
30 minutes before the blood sample is drawn.
Talk to your doctor
about any concerns you have regarding the need for the test, its risks, how it
will be done, or what the results will mean. To help you understand the
importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
The health professional taking a sample
of your blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
For a secretin test, a blood sample is drawn and then the
digestive hormone secretin is injected into a vein in your arm. Additional
blood samples are drawn at the time of the injection, then every 5 minutes
until 15 minutes have passed, and then again at 30 minutes after the secretin