General information
Gastrin is an important gastrointestinal neuropeptide that is closely
related to cholecystokinin and serves as one of the major stimuli of
gastric acid secretion. The diagnostic utility of measurement of serum
gastrin concentrations was studied in the 80’s and serum gastrin
concentration remains the diagnostic test of choice for the diagnosis
of gastrinoma. Gastrinomas are neuroendocrine tumors, usually located
in the pancreas, that lead to increased production and secretion
of gastric acid and in turn can cause gastric and duodenal ulcers leading to chronic vomiting, weight loss, and other clinical signs of
chronic upper GI disease.
Interpretation
The reference range for serum gastrin concentration in dogs
using this assay was established as < 27.8 ng/L, but most normal dogs
will have undetectable serum gastrin concentrations. More work remains
to be done to identify new uses for this assay. For now, the assay will
serve as a diagnostic tool for dogs with chronic vomiting that are
suspected of having a gastrinoma. Also, until a more precise cut-off
value for the diagnosis of a gastrinoma can be determined, we would
recommend using the traditional cut-off value of 10 times the upper
limit of the reference range, or > 278 ng/L.
As in the past, this cut-off
value, borrowed from human medicine, is likely rather conservative
in dogs and reflects a high prevalence of chronic atrophic gastritis in
humans, which can cause severely elevated serum gastrin concentrations.
In dogs, differential causes of elevated serum gastrin concentrations
are chronic renal failure, gastric outlet obstruction, small intestinal
resection, immunoproliferative enteropathy of Basenji dogs, gastric
dilatation-volvulus, and administration of proton pump inhibitors. All
of these differential diagnoses are considerably easier to rule out than
atrophic gastropathy in humans. Therefore, a less than 10-fold elevation
of serum gastrin concentration may be sufficient to diagnose a gastrinoma
if other differential diagnoses have been carefully ruled out.
