Pentagastrin is a drug that mimics the action of a natural hormone in the body. This hormone, gastrin, stimulates the stomach to produce acid. Doctors can take advantage of the similar effect pentagastrin has to diagnose stomach problems in patients.
The stomach is made up of different cells, some of which secrete substances to aid digestion and help normal functioning of the organ. One such substance is the hormone gastrin, which has several biological effects. When food enters the stomach, especially protein and calcium, the stomach releases gastrin into the bloodstream. Gastrin signals to other cells in the stomach and in the intestine to produce acid to help digest the food. The hormone also promotes gastric cell growth and may affect the rate of movement of food through the stomach.
Gastrin occurs naturally in the body as a group of similar molecules. All of these forms of gastrin have an identical section of five amino acids at one end, which is known as pentagastrin. It is only this section that is essential for function. This small section alone can therefore cause acid to be produced. Certain illnesses and conditions affect acid production, and by administering pentagastrin, doctors can gain information to help diagnose the problem.
Conditions that can be diagnosed through pentagastrin testing include stomach cancer, pernicious anemia, and gastritis. These illnesses can affect the ability of the stomach to produce acid. Gastric ulcer surgery can also lower acid production. Some conditions, such as Zollinger-Ellis cancer or an untreated stomach ulcer, can cause raised acid levels, which can also be measured after a pentagastrin test.
This test is available as an injection, although nasal inhalation of a powder is another method of administration. Fasting is necessary prior to the test, and acid production begins about 10 minutes after administration. Stomach acid samples are then collected and tested.
People with liver problems, biliary disease, or pancreatitis may not be suitable candidates for pentagastrin tests. Stomach ulcers may also be made worse by the test. In addition, it is unknown whether the substance is harmful to pregnant or breastfeeding women and their babies or if it is safe for children.
A rare side effect of pentagastrin is an allergic reaction. Adverse effects such as dizziness, lethargy, and numbness are also possible. More common, although less severe, side effects are gastrointestinal. Vomiting, pain in the stomach, and a feeling of needing to move the bowels are all possible and temporary side effects.