Serum Gastrin-17 (Fasting)

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

This test requires fasting before sample collection.

Purpose of the Test

To detect an overproduction of gastrin, to help diagnose Zollinger-Ellison syndrome (ZE syndrome), to help diagnose multiple endocrine neoplasia type 1 (MEN-1) and to monitor for recurrence of a gastrin-producing tumour (gastrinoma)

When this test is required

A gastrin test may be used when you have diarrhoea, stomach pain, and/or recurrent peptic ulcers that your doctor suspects are due to excess gastrin production. A gastrin stimulation test may be used when a gastrin level is moderately elevated and the doctor suspects the patient has a gastrinoma. When you have had a gastrin-producing tumour removed, a gastrin test may be used periodically as a screening test to monitor for recurrence.

What the Test Detects

This test measures the amount of gastrin in the blood. Gastrin is a hormone that regulates the production of acid in the stomach. It is produced by special cells called G-cells in the stomach during the digestive process. When food is eaten, the stomach becomes less acidic, promoting gastrin production. Gastrin in turn stimulates parietal cells to produce stomach acid. As acidity increases in the stomach, food is broken down and…This test measures the amount of gastrin in the blood. Gastrin is a hormone that regulates the production of acid in the stomach. It is produced by special cells called G-cells in the stomach during the digestive process. When food is eaten, the stomach becomes less acidic, promoting gastrin production. Gastrin in turn stimulates parietal cells to produce stomach acid. As acidity increases in the stomach, food is broken down and gastrin production falls. This feedback system normally results in low to moderate levels of gastrin in the blood. Rare conditions such as G-cell hyperplasia and Zollinger-Ellison (ZE) syndrome can cause an overproduction of gastrin and stomach acid. These conditions can lead to peptic ulcers that can be difficult to treat. ZE syndrome is characterised by high gastrin levels, greatly increased stomach acid production, and by peptic ulcers due to gastrin-producing tumours called gastrinomas. Gastrinomas can form in the pancreas, the duodenum and rarely in other parts of the body. More than half of these tumours are malignant and can spread to other parts of the body, such as the liver. Even tiny tumours can produce large quantities of gastrin. How is the sample collected for testing? A blood sample is taken 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 doctor may also ask you to stop taking certain stomach medicines for several days before the test. See MoreSee Less

Preparation for the Test

You should fast for 12 hours and avoid alcohol for 24 hours before the test. Your doctor may also ask you to stop taking certain stomach medications before the test. Gastrin can increase with medications such as proton pump inhibitors (PPI) which block acid production in the stomach and H2 blockers which reduce the amount of acid produced by the gastric parietal cells. Before a blood sample is taken for a baseline gastrin level H2 blockers including ranitidine, cimetidine, famotidine or nizatidine should be stopped for 72 hours and PPIs including omeprazole, lansoprazole or pantoprazole should be stopped for 2 weeks prior to testing.

Sample Requirements

A blood sample taken from a vein in your arm.

Additional Notes

Gastrinomas can affect anyone, but patients 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 tumours 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 medicines) such as ibuprofen.Increases in gastrin concentration with age may reflect a general decrease in the ability to produce stomach acid.

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