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Gastrin

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Formal name: Gastrin
Related tests: Helicobacter pylori, Gastric Acid

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The Test Sample

What is being tested?

Gastrin is a hormone produced by "G-cells" in the part of the stomach called the antrum. It regulates the production of acid in the body of 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 antrum of the stomach becomes distended and the presence of food stimulates the release of gastrin. Gastrin in turn stimulates parietal cells to produce gastric acid. Acidity helps to digest food and the rise in acidity eventually suppresses gastrin release. This feedback system normally results in low concentrations of gastrin in the blood, especially in the fasting state. Rare conditions such as G-cell hyperplasia and gastrinomas, including 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.

Gastrinomas are gastrin-producing tumors. ZE syndrome is a condition caused by the presence of one or more gastrinomas and is characterized by high gastrin levels, greatly increased gastric acid production, and by peptic ulcers. Gastrinomas usually form in the pancreas, even though the endocrine cells of the pancreas do not normally make gastrin. 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 healthcare practitioner may also ask you to refrain from taking certain stomach medications for several days prior to the test. Medications that can increase gastrin levels include antacids, H2-blocking agents (such as cimetidine), and proton pump inhibitors (such as omeprazole). These prevent the normal negative feedback in which acidity suppresses gastrin production.