| Subject | Contents |
| Definition | A test that assesses the quantity and acidity of stomach contents. |
| Alternative Names | Gastric acid |
| How the test is performed | The gastric residue is what remains in the stomach after fasting. This fluid is aspirated through a tube inserted through the esophagus and analyzed. To test the capacity of the parietal cells in the stomach to secrete acid, gastrin may be given subcutaneously (just under the skin), intramuscularly, or intravenously. The stomach contents are then aspirated and analyzed. Another test involves insulin-induced hypoglycemia (enough insulin is given subcutaneously or intravenously to cause the blood sugar to decrease), which causes the vagus nerve to stimulate the release of gastrin. After a short time, the stomach contents are aspirated and analyzed. |
| How to prepare for the test | Fast for 4-6 hours before the test. Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:Infant test or procedure preparation (birth to 1 year) Toddler test or procedure preparation (1 to 3 years) Preschooler test or procedure preparation (3 to 6 years) Schoolage test or procedure preparation (6 to 12 years) Adolescent test or procedure preparation (12 to 18 years) |
| How the test will feel | There may be some discomfort and a gagging sensation as the tube is passed via the nose or mouth, down the esophagus, and into the stomach. |
| Why the test is performed | This test may be used to test for the cause of ulcers , to detect duodenal regurgitation, to evaluate the cause of malabsorption , to assess the adequacy of anti-ulcer medications, and to evaluate secretion of gastrin . |
| Normal Values | Normally the volume of the stomach residue is 20 to 100 ml, the pH is acidic (1.5 to 3.5). Note: ml = milliliter |
| What abnormal results mean | Ulcers may be caused by delayed emptying or increased secretion of acid. The presence of bile in the stomach indicates regurgitation from the duodenum (which may be seen after a partial gastrectomy ). See also gastroesophageal reflux disease . Decreased stomach acid or gastrin can cause malabsorption (inadequate absorption of nutrients from the intestinal tract). Increased gastrin causes increased secretion of acid and may lead to ulcers ( Zollinger-Ellison syndrome ). |
| What the risks are | The primary risk is associated with placement of the tube into the stomach. There is a slight risk of the tube being placed into the lungs instead of the stomach, correct placement of the tube should be verified prior to continuing with the test. If the test includes injection of insulin, there is a risk of inducing hypoglycemia ( low blood sugar ) symptoms. |
| Special considerations | Not applicable. |
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