The stomach acid test is used to measure the quantity and acidity of stomach contents.

This test may be used for a number of reasons:

• To check if anti-ulcer medications are working
• To check if material is coming back up from the small intestine
• To evaluate the cause of malabsorption of nutrients from the intestines
• To test for the cause of ulcers

After not eating for a period of time, fluid is all that remains in the stomach. This fluid can be removed via a tube inserted through the esophagus (food pipe).

To test the ability of cells in the stomach to secrete acid, gastrin may be injected just under the skin, into a muscle, or into a vein. The stomach contents are then removed and analyzed.

Another test involves insulin-induced hypoglycemia. Enough insulin is given under the skin or through a vein to cause the blood sugar to decrease. This causes the vagus nerve to stimulate the release of gastrin. After a short time, the stomach contents are removed and analyzed.

You will be asked not to eat or drink for 4 - 6 hours before the test.

You may notice some discomfort or a gagging feeling as the tube is passed through your nose or mouth, and down your esophagus.