Stomach acid test
The stomach acid test is used to measure the quantity and acidity of stomach contents.
Gastric acid secretion test
How the test is performed
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 into the stomach through the esophagus (food pipe).
To test the ability of cells in the stomach to release acid, gastrin may be injected just under the skin, into a muscle, or into a vein. The stomach contents are then removed and analyzed.
How to prepare for the test
You will be asked not to eat or drink for 4 - 6 hours before the test.
How the test will feel
You may notice some discomfort or a gagging feeling as the tube is passed through your nose or mouth, and down your esophagus.
Why the test is performed
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 test for the cause of ulcers
Normally the volume of the stomach fluid is 20 to 100 mL and the pH is acidic (1.5 to 3.5). In some situations, these numbers are converted to actual acid production in units of milliequivalents per hour.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
- Decreased levels of stomach acid or gastrin can cause malabsorption.
- Increased levels of gastrin can cause increased release of acid and may lead to ulcers (Zollinger-Ellison syndrome).
- The presence of bile in the stomach indicates material is backing up from the small intestine ( duodenum). This may happen after part of the stomach is removed with surgery.
What the risks are
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. The health care provider will be sure the tube is correctly placed before continuing with the test.
Scubert ML, Kaunitz JD. Gastric secretion. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 49.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.