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The urease test is a laboratory test used to identify bacteria by detecting the activity of an enzyme, urease, that bacteria may or may not have. Urease is an enzyme responsible for the degradation of urea into ammonia and bicarbonate, which increases the pH of the place where it is present, favoring the proliferation of the microorganism.
This test is mainly used in the diagnosis of Helicobacter pylori, or H. pylori, infection, which is responsible for various problems such as gastritis, esophagitis, duodenitis, ulcer and stomach cancer.
Thus, if H. pylori infection is suspected, the gastroenterologist may perform the urease test during endoscopy. If so, treatment is started quickly with the aim of preventing the progression of the disease and relieving the person's symptoms.
How the test is done
When the urease test is performed as a routine laboratory test, no preparation for the exam is required. However, if it is performed during endoscopy, it is important that the person follows all the rules of the exam, such as avoiding using antacid medicines and fasting for at least 8 hours. The urease test is carried out in the laboratory through the analysis of the material collected, and the isolation of the microorganism and biochemical identification tests are carried out, including the urease test.
In the case of the urease test to detect H. pylori infection, the test is performed during the upper endoscopy exam, which is an exam that evaluates the he alth of the esophagus and stomach, without causing pain or discomfort on the patient and the result can be evaluated in a few minutes.
During the examination, a small piece of the stomach wall is removed and placed in a bottle containing urea and a pH indicator. If after a few minutes the medium changes color from yellow to pink/red the test is said to be urease positive, confirming H. pylori infection. See what symptoms may indicate an H. pylori infection.
How to understand the result
The result of the urease test is given from the color change of the medium in which the test is being performed. So the results can be:
- Positive, which means that the person has an infection with a bacterium that has the urease enzyme, such as H. pylori, Staphylococcus saprophyticus, Staphylococcus epidermidis, Proteus spp. and Klebsiella pneumoniae, for example;
- Negative when there is no change in the color of the medium, indicating that there is no infection by bacteria that have the enzyme. In the case of a search for H. pylori, the negative result indicates that the person is not a carrier of this bacterium.
It is important that the results are interpreted within 24 hours so that there is no chance of false-positive results, which are those that, due to the aging of the medium, the urea starts to be degraded, which can change the color.