What is Gastrin level?

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. The 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 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.

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.

How is it used?

The gastrin test is primarily used to help detect excess production of gastrin and gastric acid. It is used to help diagnose gastrin-producing tumors called gastrinomas, Zollinger-Ellison (ZE) syndrome, and hyperplasia of G-cells. G-cells are specialized cells in the stomach that produce gastrin, which in turn increases the production of gastric acid.

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

A gastrin stimulation test therefore may be used to provide additional information if the initial gastrin test result is moderately but not significantly elevated and the healthcare practitioner 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. The other (benign) causes of elevated gastrin will not show an increase after secretin administration.

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