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.
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.
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.
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.
This article was last reviewed on November 29, 2012. | This article was last modified on August 30, 2013.
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