Gastryna belongs to enterohormones, i.e. gastrointestinal hormones. It affects the proper functioning of the digestive system. Gastrin concentration testing is rarely ordered and never without basic tests and determination of acidity of gastric contents, because without them it is completely unreliable and pointless.
Gastrynais a mixture of peptides - preprogastrin, progastrin, gastrin-34, gastrin-17, gastrin-14. The 14 amino acid peptide is the most active. All forms, also synthesized peptides with gastrin activity, share a common sequence of 4 amino acids at the N-terminus of the molecule: -Trp -Met -Asp -Phe -NH2. Pentagastrin has found the most widespread use among synthetic forms. Gastrin is produced by G cells located in the pyloric part of the stomach and in the initial part of the duodenum. Food is the stimulus that most strongly stimulates the secretion of the gastric mucosa. There are three secretory phases of the stomach and in all of them the secretion of gastrin takes place:
- in the cephalic (cerebral) phase - it is small and takes place under the influence of the central nervous system, is stimulated by GRP (gastrin-releasing peptide), which is released at the ends of neurons, near G cells, the cephalic phase determines the secretion of approx. 20% of the daily volume of gastric juice
- in the visceral (gastric) phase - gastrin plays a key role, its secretion is very intensified, it is stimulated by GRP; the visceral phase is responsible for over 60% of the daily volume of gastric juice
- in the intestinal phase - gastrin is secreted as a result of direct and indirect stimulation.
Gastryna: action
- stimulates the growth processes of the gastric, duodenal and large intestine mucosa
- increases the secretion of hydrochloric acid and pepsin by the stomach
- increases the secretion of water and electrolytes in pancreatic juice and bile
- contraction of the lower esophageal sphincter
- increases the peristalsis of the digestive tract
- increases blood flow through the gastric mucosa
Gastryna: secretion
Factors increasing gastrin secretion
- consumption of proteins, peptones, amino acids, coffee and alcohol is a direct stimulus stimulating gastrin secretion; fats and carbohydrates do not stimulate secretionhormone
- mechanical stretching of the stomach wall by stimulating the intramural nerve plexus that releases acetylcholine on nerve endings, which - through the receptor pathway - stimulates the function of G cells
- presence of Ca2 + ions
Factors reducing gastrin secretion
- acidification of the stomach with content with a pH of 4.0 to 1.0
- somatostatin
- secretary
The secretion of gastrin and the production of hydrochloric acid are mutually regulated by negative feedback. This phenomenon is called antral autoregulation.
Indications for gastrin testing
- gastric and / or duodenal ulcer unresponsive and / or unrelated to infectionH. pyloriand / or multiple ulcerations and / or accompanying unexplained diarrhea
- suspicion of Zollinger-Ellison syndrome (presence of a gastrin producing tumor - Gastrinoma)
- taking strong agents that inhibit gastric acid secretion (H2 receptor antagonists, proton pump inhibitors)
- condition after bowel resection
- diagnosis of Addison-Biermer anemia
- suspected chronic atrophic gastritis type A (gastritis A)
- kidney failure
The measurement of gastrin concentration alone has little diagnostic value. It is a highly specialized examination, usually ordered by a gastroenterologist as part of a wider diagnosis.
Gastrin test: run
Measurements are made on several blood samples, 2-3 ml in volume, collected in test tubes without anticoagulant in the following days. The patient should be on an empty stomach, which means that for at least 6-8 hours. did not take food or fluids.