From the Guidelines
A serum gastrin level is important in a patient with a bleeding duodenal ulcer when there is suspicion of Zollinger-Ellison syndrome (ZES) or gastrinoma, particularly in cases of recurrent or multiple ulcers, ulcers in unusual locations, or refractory to standard treatment. This suspicion should be raised when the patient has a family history of multiple endocrine neoplasia type 1 (MEN-1) or presents with other clinical clues such as diarrhea, symptoms of gastroesophageal reflux disease despite treatment, or complications like perforation or bleeding despite appropriate therapy 1.
Key Considerations
- The fasting serum gastrin level should be measured after the patient has been off proton pump inhibitors for at least 1 week (if possible), as these medications can falsely elevate gastrin levels 1.
- A level greater than 1000 pg/mL is highly suggestive of ZES, while levels between 200-1000 pg/mL may require additional testing such as a secretin stimulation test for confirmation.
- Identifying ZES is crucial because these patients require more aggressive acid suppression therapy (often high-dose proton pump inhibitors like omeprazole 60-120 mg daily), and they need evaluation for underlying tumors that may require surgical intervention 1.
Clinical Context
In the context of a bleeding duodenal ulcer, it is essential to consider the potential for ZES or gastrinoma, especially when the clinical presentation is atypical or refractory to standard management. The measurement of serum gastrin levels, along with other diagnostic tests, can help in identifying these conditions and guiding appropriate treatment.
Diagnostic Approach
The diagnostic approach should include:
- Measurement of fasting serum gastrin level after withdrawal of proton pump inhibitors.
- Consideration of secretin stimulation test for confirmation in cases with intermediate gastrin levels.
- Evaluation for underlying tumors, particularly in the duodenum, and consideration of MEN-1 syndrome.
- Use of other diagnostic tools such as imaging studies (e.g., multiphasic CT/MRI scan) and tests for Helicobacter pylori infection, as appropriate 1.
From the Research
Importance of Serum Gastrin Level in Bleeding Duodenal Ulcer
- A serum gastrin level is important in a patient who presents with a bleeding duodenal ulcer when Zollinger-Ellison syndrome (ZES) is suspected 2, 3, 4.
- ZES is a distinct syndrome characterized by hyperchlorhydria-induced peptic ulcer disease and chronic diarrhea, caused by a gastrin-excess state due to a duodenal or pancreatic neuroendocrine tumor referred to as gastrinoma 2.
- Fasting serum gastrin level measurement serves as an initial and fundamental diagnostic test for ZES, with a sensitivity of 99% 2.
- A serum gastrin level greater than 100 pg/mL is indicative of gastrinoma, while a level higher than 1000 pg/mL, in the presence of gastric pH <2, is considered diagnostic 2.
Diagnostic Considerations
- Before considering ZES, it is essential to rule out other common causes of hypergastrinemia, such as atrophic gastritis, Helicobacter pylori (H. pylori)-associated pangastritis, renal failure, vagotomy, gastric outlet obstruction, and retained antrum syndrome 2.
- The secretin stimulation test and the calcium gluconate injection test are classic adjuvant diagnostic techniques used to differentiate ZES from other hypergastrinemic states 2.
- Localization of the primary tumor and its metastases is the next diagnostic step when gastrinoma-associated ZES is suspected or biochemically confirmed 2, 4.