Patient Test Information

Gastrin

Formal name:

Gastrin

Related tests:

Helicobacter pylori, Gastric Acid

Why Get Tested?

To detect an overproduction of gastrin, to help diagnose Zollinger-Ellison syndrome and G-cell hyperplasia, and to monitor for recurrence of a gastrin-producing tumor (gastrinoma)

When to Get Tested?

When you have peptic ulcers and/or diarrhea and abdominal pain that your doctor suspects is caused by excess gastrin; periodically to monitor for a gastrinoma recurrence

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

You should fast for 12 hours and avoid alcohol for 24 hours prior to the test. Your doctor may also ask you to refrain from taking certain stomach medications for several days prior to the test.

How is it used?

The gastrin test is primarily ordered to help detect excess production of gastrin and gastric acid. It is ordered to help diagnose gastrin-producing tumors called gastrinomas, Zollinger-Ellison (ZE) syndrome, and hyperplasia of G-cells, specialized cells in the stomach that produce gastrin. It may be ordered if a person has abdominal pain, diarrhea, and recurrent peptic ulcers.

A gastrin test may also be ordered to monitor for recurrence following the surgical removal of a gastrinoma.

A gastrin stimulation test may be used to provide additional information if the initial gastrin test result is moderately but not significantly elevated and the doctor suspects that a person's symptoms are due to a gastrinoma. This procedure involves collecting a baseline gastrin sample, giving the patient a chemical (typically the hormone secretin) to stimulate gastrin production, and then collecting additional blood samples at timed intervals for gastrin testing.

A measurement of gastric acid pH level may sometimes be ordered along with or following a gastrin test to help diagnose ZE syndrome.

When is it ordered?

A gastrin test may be ordered when a person has diarrhea, abdominal pain, and/or recurrent peptic ulcers that the doctor suspects are due to excess gastrin production. A gastrin stimulation test may be ordered when a gastrin level is moderately elevated and the doctor suspects that a person has a gastrinoma.

When a gastrin-producing tumor has been removed, a gastrin test may be ordered periodically as a screening test to monitor for recurrence.

What does the test result mean?

Low or normal concentrations of gastrin are not typically of concern. Moderately increased levels may be seen with a variety of conditions such as ZE syndrome, G-cell hyperplasia, atrophic gastritis, pernicious anemia, a pyloric obstruction (blockage at the junction of the stomach and duodenum), and chronic kidney failure.

Greatly increased levels of gastrin in symptomatic individuals and concentrations of gastrin that increase significantly during a gastrin stimulation test indicate the likelihood that a person has ZE syndrome and one or more gastrinomas. Imaging tests may be ordered as a follow up to high gastrin concentrations to locate the gastrinoma(s). The quantity of gastrin produced is not related to either the tumor size or to the number of tumors. Even tiny tumors can produce large amounts of gastrin.

Gastrin levels that were initially low after the surgical removal of a gastrinoma and then increase may signal a recurrence of the tumor. Concentrations that do not decrease after treatment may indicate that the treatment has not been fully effective.

Is there anything else I should know?

Gastrinomas can affect anyone, but people who have an inherited condition called MEN-1 (Multiple Endocrine Neoplasia, type 1) are at an increased risk. These people have genetic alterations that increase their lifetime risk of developing tumors in their pancreas or in another of their endocrine glands.

It is important to note that most stomach ulcers are not due to gastrinomas. They are commonly associated with Helicobacter pylori infections and sometimes with the use of NSAIDs (nonsteroidal anti-inflammatory drugs) such as ibuprofen.

Gastrin levels commonly increase with age and with prolonged use of medications such as antacids and proton pump inhibitors that neutralize or inhibit the production of stomach acid. They will also typically be elevated in people who are not fasting. Increases in gastrin concentration with age may reflect a general decrease in the ability to produce stomach acid.

Gastrin blood levels follow a circadian rhythm. This means that they will be at their lowest between about 3 to 7 AM. Concentrations will be higher during the day and will fluctuate in response to meals.

What is being tested?

Gastrin is a hormone produced by "G-cells" in the stomach. It regulates the production of acid in the stomach during the digestive process. This test measures the amount of gastrin in the blood to help evaluate an individual with recurrent peptic ulcers and/or other serious abdominal symptoms.

When food is eaten, the stomach becomes less acidic, stimulating the release of gastrin. Gastrin in turn stimulates parietal cells to produce gastric acid. As acidity increases in the stomach, food is broken down and gastrin release is suppressed. This feedback system normally results in low to moderate concentrations of gastrin in the blood. Rare conditions such as G-cell hyperplasia and Zollinger-Ellison (ZE) syndrome can cause an overproduction of gastrin and gastric acid. This can lead to aggressive peptic ulcers that can be difficult to treat.

ZE syndrome is characterized by high gastrin levels, greatly increased gastric acid production, and by peptic ulcers due to gastrin-producing tumors called gastrinomas. Gastrinomas can form in the pancreas, the duodenum, and rarely in other parts of the body. More than half of them are malignant - causing cancer that can spread to other parts of the body, such as the liver. Even tiny tumors can produce large quantities of gastrin.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

You should fast for 12 hours and avoid alcohol for 24 hours prior to the test. Your doctor may also ask you to refrain from taking certain stomach medications for several days prior to the test.

  1. What is Zollinger-Ellison syndrome?

    Zollinger-Ellison (ZE) syndrome is a rare disease of the gastrointestinal tract. It is characterized by severe recurrent peptic ulcers in the stomach, duodenum and/or the upper portion of the small intestine. The ulcers are caused by a greatly increased amount of stomach acid due to high levels of gastrin, the hormone that stimulates stomach acid production. In ZE, high gastrin levels are caused by gastrin-producing tumors called gastrinomas, which usually form in the duodenum but can be found in the pancreas and rarely in other parts of the body. More than half of them are malignant and can metastasize to other parts of the body, such as the liver. The tumors must be removed surgically, and sometimes total removal of the stomach is necessary to control the acid production. For more on this, see the Related Pages tab. 

  2. How long will it take to get the results of my gastrin test? 

    Gastrin testing is performed using specialized equipment in a laboratory and not every laboratory will offer gastrin testing. In some cases, your sample may need to be sent to a reference laboratory and results may take a few days.

  3. Can't I just take stomach medicines to address my excess gastrin and stomach acid?

    Stomach medications such as proton pump inhibitors may be prescribed as part of your treatment, but it is important to diagnose your underlying condition. Although gastrinomas are rare, more than half of them are cancerous and can spread to other parts of your body.