The stomach acid test is a test that measures the quantity and acidity of stomach contents.

After a period of fasting, 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 four to six 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.