Gastrin in serum

Gastrin is a hormone of polypeptide character (the molecule consists of 17 amino acids, Mr = 2,100), which occurs in three forms: the basic molecule is G-17 (little gastrin), the others are G-34 (big gastrin) and G-13 ( mini gastrin with a shortened chain to 13 amino acids). A pentapeptide with a C-terminal gastrin sequence (β-Ala-Trp-Met-Asp-Phe-NH2), called pentagastrin, is used to stimulate gastric acidity.

Gastrin level
Serum gastrin levels are usually determined by the RIA method, there are also ELISA variants of immunochemical evidence. Normal values of 25–100 ng / l are significantly increased especially in Zollinger-Ellison syndrome (gastrinoma, pancreatic tumor with overproduction of gastrin), when we show a 10–1000-fold increase in gastrin levels, which, however, fluctuates significantly during the day; 20-40% can capture normal gastrin levels. Due to the existence of three forms of gastrin, the result of the assay depends on the type of antibody used in the test. Methods for the determination of gastrin are standardized for synthetic gastrin G-17, the determination of forms G-34 and G-13 depends on the cross-reactivity with the respective antibody. The normal ratio of forms G-13: G-17: G-34 is 8: 2: 1, on an empty stomach there is a higher proportion of forms G-34, after eating forms G-17 and G-13.

Determination of gastrin
The determination of gastrin is part of the gastrin stimulation test, where we determine a 90-minute profile (in 9 serum samples) after stimulation with insulin, secretin or Ca-gluconate. The determination of gastrin-17, pepsinogen I and antibodies to Helicobacter pylori class IgG is offered by the so-called GastroPanel, which is a non-invasive, laboratory parameter to assess Helicobacter pylori infection, atrophic gastritis and gastric cancer risk. The issue of determination of gastrin on an empty stomach and after stimulation and the diagnostic significance in the pathology of gastroduodenal diseases, including gastric cancer, are also discussed.

Source

 * With permission of the author taken from: KOCNA, Petr. GastroLab : MiniEncyklopedia of laboratory methods in gastroenterology [online]. ©2002. Last revision 2011-01-08, [cit. 2011-03-04]. < http://www1.lf1.cuni.cz/~kocna/glab/glency1.htm >.