Urease Test: How It's Done & What Results Mean

Updated in March 2024

The urease test is a lab test that identify the type of bacteria present in the stomach. It works by detecting an enzyme, urease, which the bacteria may or may not possess. Urease is an enzyme that breaks down urea into ammonia and bicarbonate, which increases the pH of the location where ever it is present.

The urease test is mainly used to diagnose H. pylori infections, which can cause several gastric problems such as gastritis, esophagitis, duodenitis, ulcers and even stomach cancer.

Also recommended: 6 H. Pylori Symptoms to Monitor (with Online Symptoms Quiz) tuasaude.com/en/h-pylori-symptoms

If an H. pylori infection is suspected, the gastroenterologist may perform a urease test during endoscopy. If positive, treatment is started promptly with the aim of symptom relief and preventing the disease from worsening.

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How the test is done

A urease test that is performed during endoscopy requires preparation like avoiding using antacid medications and fasting for at least 8 hours prior.

One way the urease test can be done is in the laboratory setting. The laboratory collects the specimen collected by the doctor and performs the urease test by isolating the microorganism and completing the biochemical identification test.

Urease tests that are used to detect H. pylori infection can also be performed during the upper endoscopy, which is an procedure that evaluates the health of the esophagus and stomach. The test can be done without causing pain or discomfort to the patient and the result can be evaluated in just a few minutes.

During the examination, a small piece of the stomach wall is removed and placed in a vial containing urea and a pH indicator. If after a few minutes the medium changes color from yellow to pink/red, the test is urease positive, confirming H. pylori infection.

What results mean

The result of the urease test may be:

  • Urease-positive: means that the person has an infection with a bacteria that has the urease enzyme, such as H. pylori, Staphylococcus saprophyticus, Staphylococcus epidermidis, Proteus spp. and Klebsiella pneumoniae;
  • Urease-negative: there is no infection with any bacteria that may have this enzyme. When done in those with suspected H. pylori, a negative result indicates that the person is not infected

It is important that the results are interpreted within 24 hours so that there is no chance of false-positive results. These can occur when the specimen starts to age, and the urea starts to breakdown, which can change the color.