The stomach acid test is used to measure the amount of acid in the stomach. It also measures the level of acidity in stomach contents.
The test is done after you have not eaten for a while so fluid is all that remains in the stomach. Stomach fluid is removed through a tube that is inserted into the stomach through the esophagus (food pipe).
A hormone called gastrin may be injected into your body. This is done to test the ability of the cells in the stomach to release acid. The stomach contents are then removed and analyzed.
You will be asked not to eat or drink for 4 to 6 hours before the test.
You may have some discomfort or a gagging feeling as the tube is inserted.
Your health care provider may recommend this test for the following reasons:
The normal volume of the stomach fluid is 20 to 100 mL and the pH is acidic (1.5 to 3.5). These numbers are converted to actual acid production in units of milliequivalents per hour (mEq/hr) in some cases.
Note: Normal value ranges may vary slightly depending on the lab doing the test. Talk to your provider about the meaning of your specific test results.
Abnormal results may indicate:
There is a slight risk of the tube being placed through the windpipe and into the lungs instead of through the esophagus and into the stomach.
Reviewed By: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.