Gastrin is a hormone found in the human body. It is produced by cells in the lining of the stomach, and its purpose is to regulate the secretion of digestive acid. Although there are other hormones involved in this process, gastrin is the primary regulator for the stomach acid. The cells of the stomach responsible for making this substance are called G cells.
The very act of consuming food stimulates the production of the hormone. As a person eats, food enters his stomach, and G cells stimulate the release of gastrin into the blood. Levels begin to rise in the blood, triggering the release of gastric acid. This acid aids in the digestion of food. Eventually, enough gastric acid is produced, and the hormone's levels begin to drop once more.
Besides the stomach, this substance also has a role to play with other organs in the human body. It aids the intestines, liver, and pancreas as well, though its effects are minor in these organs. In the pancreas, it serves to trigger the production of digestive enzymes. In the liver, it aids in bile production. Its role in the intestines is for aiding in the movement of food through the lower part of the digestive tract.
Sometimes it is necessary for doctors to check a person's gastrin production. This may be done, for example, when diseases involving the digestive system are suspected. For example, this test may be performed to check for abnormal growths in a person's pancreas or in the cells of his stomach lining. It may also be done to reveal tumors in the intestine. Such testing may also prove helpful for discovering diseases like pernicious anemia, a type of blood disease.
To test for gastrin, medical professionals typically perform an intravenous secretin test. This involves taking a sample of the patient's blood and then injecting a digestive hormone called secretin into one of his veins. Another blood sample is taken when the patient is injected, and additional sampling follows every five minutes after injection for the first quarter of an hour. Finally, another blood sample is taken at 30 minutes following the secretin injection. Results are usually available within just a couple of days of testing.
While high gastrin levels may indicate tumors or blood disease, there are other conditions associated with elevated levels of the hormone. For example, kidney failure and certain types of ulcers may be at fault. On the other hand, low levels of the hormone can indicate medical conditions as well. For example, low levels have been associated with hypothyroidism.