Gastrin

What is Gastrin?

Gastrin is a hormone that helps your digestive system work properly. Hormones are chemicals in your bloodstream that tell different parts of your body what to do and when to do it.

What does gastrin do?

Gastrin has several important functions. Gastrin tells:

• Your stomach to release gastric acid (hydrochloric acid)
• The muscles in your stomach to contract (gastric motility)
• Your stomach lining (mucosa) to constantly replenish itself

With the help of a hormone called cholecystokinin, gastrin also triggers your gallbladder and pancreas to contract.

Where is gastrin produced?

Organs in your digestive system produce and release gastrin as part of the digestive process. The hormone comes from cells in the lining of your organs. These are called G-cells, which stands for gastrin cells.

Most gastrin comes from the bottom part of your stomach (the antrum). The gastric glands within your stomach lining contain G-cells. The first part of your small intestine (duodenum) and pancreas also make some gastrin.

What stimulates gastrin release?

Your brain and digestive system are in constant communication. They talk to each other through your vagal nerves. So, even thinking about eating is enough to get the process started.

Vagal nerve fibers in your brain signal to those in your stomach. They tell them to get ready for digestion by releasing gastrin. Once you start eating, nerves in your stomach detect food inside and release more.

Some of the signals that stimulate gastrin to release include:

• Rising pH levels in your stomach (when there’s less acid)
• Stretching of your stomach walls to make room for food
• The presence of certain foods, especially proteins

Gastrin triggers the release of gastric acid. This, in turn, activates the digestive enzyme, pepsin. These substances help break down proteins in your stomach. Gastrin also activates your stomach’s muscle movements.

What stops the release of gastrin?

When food leaves your stomach and enters your duodenum, gastrin release stops. This triggers the next phase of digestion. As food leaves and acid levels in your stomach rise, gastrin starts to reduce.

Food entering your duodenum triggers your gallbladder and pancreas to release their digestive juices. Then, your digestive system releases the hormone somatostatin, which turns the other hormones off.

What medical test checks gastrin levels?

A gastrin test is a type of blood test. It checks the levels of gastrin moving through your blood. A healthcare provider draws a small sample of your blood through a needle and sends it to a lab.

Why do my gastrin levels matter?

Healthcare providers may check your gastrin levels to make sure they aren’t too high. Elevated gastrin levels — called hypergastrinemia — can point to stomach or intestinal problems.

Too much gastrin can lead to too much gastric acid in your stomach and duodenum. This can wear down your stomach lining, which can cause ulcers (peptic ulcer disease). It can also contribute to chronic acid reflux (GERD).

Your provider might want to check your gastrin levels if you have ulcers or GERD that doesn’t get better with medicine.

What conditions and disorders could involve high gastrin levels?

You might have high gastrin and gastric acid levels if you have gastrinomas. These are a type of pancreatic neuroendocrine tumor (PET) that releases gastrin. They can be cancerous or noncancerous.

Conditions that cause gastrinomas include:

• Zollinger-Ellison syndrome
• Multiple endocrine neoplasia type 1 (MEN1)

Conditions that cause high gastrin and high gastric acid without gastrinomas include:

• Chronic kidney failure
• Gastric outlet obstruction (GOO)

You might have high gastrin with low gastric acid if you have reduced gastric acid production. This could be due to atrophic gastritis. This occurs when the acid-producing cells in your stomach lining waste away (atrophy).

Major causes of atrophic gastritis include:

• H. pylori infection
• Autoimmune atrophic gastritis

Other causes of reduced gastric acid production include:

• Acid-blocking medications, like H2 blockers or proton pump inhibitors (PPIs)
• Vagotomy

What should I do if I have symptoms of high gastrin levels?

Always see a healthcare provider about your gastrointestinal symptoms. This is especially important if you have them often or you’ve had them for a long time. Symptoms related to increased gastrin might include:

• Burning or gnawing stomach pain
• Chronic heartburn and indigestion
• Acid backwash or spitting up food and stomach juices
• Chronic sore throat and hoarseness
• Chronic diarrhea
• Digestive problems

These symptoms could suggest high gastric acid levels, atrophic gastritis, peptic ulcer disease or GERD. Gastrin may or may not be involved. But it’s important to diagnose and treat these conditions.