How is it used?
The gastrin test is primarily ordered to help detect excess production of gastrin and stomach acid. It is ordered to help diagnose gastrin-producing called gastrinomas, , and of G-cells, specialised cells in the stomach that produce gastrin. It may be ordered if a person has abdominal pain, diarrhoea, and recurrent peptic ulcers.
A gastrin test may also be ordered to monitor for recurrence following the surgical removal of a gastrinoma.
Sometimes a gastrin stimulation test may be ordered if a gastrin result is not significantly elevated, but the doctor still suspects that the patient's are due to a gastrinoma. This procedure involves collecting a baseline gastrin sample, giving the patient a chemical (typically the secretin) to stimulate gastrin production, and then drawing additional gastrin samples at timed intervals.
A measurement of gastric acid level (pH) may sometimes be ordered along with or following a gastrin test to help diagnose ZE syndrome.
When is it requested?
A gastrin test may be ordered when you have diarrhoea, abdominal pain, and/or recurrent peptic ulcers that your 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 the patient has a gastrinoma. When you have had a gastrin-producing tumour 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 followed up. Moderately increased levels may be seen with a variety of conditions such as , G-cell , atrophic gastritis, pernicious anaemia, a pyloric obstruction (blockage at the junction of the stomach and ), and kidney failure.
Gastrin levels can increase with age and with prolonged use of medications such as antacids and proton pump inhibitors that neutralise or inhibit the production of stomach acid. They will also typically be elevated in patients who are not fasting.
Greatly increased levels of gastrin in symptomatic patients 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 are typically 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 tumour size or to the number of tumours. Even tiny tumours 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 tumour. 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 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 other 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.