Gastrin – what is it, when to test, what does elevated gastrin mean?

Gastrin is a hormone secreted by the G cells of the antral part of the stomach. There is a mixture of several forms of gastrin in the serum, differing in size. Gastrin stimulates the secretion of gastric juice and the growth of the epithelium of the small and large intestines.

What is gastrin?

Gastryna It is secreted mainly in the stomach and is responsible for the secretion of hydrochloric acid and pepsinogen, which initiate the process of digesting proteins in the stomach. It is a mixture of peptides: gastrin-34, gastrin-17, preprogastrin, gastrin-14, progastrin. The most active is a peptide containing 14 amino acids. The stimuli stimulating gastrin secretion are: presence of food in the stomach, amino acids and peptides, stretching of the stomach walls and stimulation of the vagus nerve. Gastrin stimulates the secretion of gastric juice and the growth of the epithelium of the small and large intestines. Excessive secretion of it can lead to the formation of hyperacid gastric juice, which in turn causes damage to the gastric mucosa and the formation of ulcers. For this reason, excessive secretion of this hormone is suspected, among others, in people who suffer from gastric or duodenal ulcers.

Food is the stimulus that stimulates the secretion of the gastric mucosa the most. We distinguish three secretory phases of the stomach (gastrin is produced in each of them):

1. the head (cerebral) phase – 20% of the daily volume of gastric juices is produced in its course; this phase is small and occurs as a result of the central nervous system,
2. intestinal phase – gastrin secretion results from direct and indirect stimulation,
3. visceral phase – more than half of the daily volume of gastric juice is secreted, it is very intense.

Summary of the functions performed by gastrin

1. stimulates the peristalsis of the digestive tract,
2. stimulates the growth of the duodenal mucosa, stomach and large intestine,
3. increases blood flow through the gastric mucosa,
4. stimulates the secretion of hydrochloric acid and pepsins by the stomach,
5. intensifies the secretion of electrolytes and water in bile and pancreatic juice,
6. it causes the lower esophageal sphincter to contract.

What factors increase and decrease gastrin secretion?

The factors increasing the production of gastrin include:

1. the presence of Ca2 + ions,
2. consumption of alcohol, coffee, amino acids and proteins – stimulates the secretion of gastrin (as opposed to carbohydrates and fats),
3. mechanical stretching of the stomach wall.

In turn, the reduced secretion of gastrin stimulates: somatostatin, secretin and acidification of the stomach with the content of pH (from 4,0 to 1,0).

Also check which amino acids help acidify the stomach

IMPORTANT! The secretion of gastrin and the production of hydrochloric acid are subject antral self-regulation, i.e. mutual regulation based on feedback.

When do we do gastrin testing?

High gastrin concentration is observed in the course of many diseases. The main indications for performing the determination are:

1. Suspicion of a gastrin producing tumor (gastrinoma) and overgrowth of G cells in the stomach.
2. The presence of a persistent gastric or duodenal ulcer and the presence of ulcers in atypical places (distal gastrointestinal tract), recurrent after treatment; esophagitis.
3. Suspicion of Addison-Biermer anemia.
4. Taking medications that inhibit gastric acid secretion (e.g. proton pump inhibitors).
5. Condition after bowel resection.
6. Suspicion of Zollinger-Ellison syndrome (in its course there is an uncontrolled production of gastrin by the tumor).
7. Suspected renal failure (due to impaired hormone metabolism).

Gastrin test is a specialized test that is usually performed on request gastroenterologistafter a careful analysis of the patient’s medical history. Measurement of gastrin in the blood without prior basic tests and determination of gastric acidity is unreliable.

Gastrin – study

1. Material for gastrin testing: serum.
2. Preparation for the test: on an empty stomach (at least 8 hours). The material should be collected in the morning. The measurement is carried out on several blood samples with a volume of 2-3 ml, collected in the following days in test tubes without anticoagulant
3. The course of the examination: taking blood from a vein in the arm.
4. Waiting time for the gastrin result: 1 day.
5. Norm: 50-80 ng/l.
6. Comments: A single blood gastrin determination, without prior basic tests, but also gastric acidity determination, is completely unreliable and pointless.

Are there any contraindications for the test?

It is enough to take a small amount of serum to perform the test. There are no contraindications.

Does the gastrin test have any side effects?

The examination does not cause any serious complications. It can only cause fainting in people who are sensitive to the sight of blood.

When are we dealing with elevated gastrin levels?

Elevated gastrin levels may suggest:

1. Zollinger-Ellison syndrome (uncontrolled production of gastrin by the tumor),
2. taking strong medications that inhibit the secretion of gastric juice,
3. condition after bowel resection,
4. gastritis type A (atrophic),
5. Addison-Biermer anemia,
6. kidney failure.