The urease test is one of the diagnostic tests used to diagnose Helicobacter pyloria infection and monitor the effectiveness of therapy. There are two types of urease test - the rapid urease test and the urea breath test. Find out what the urease test is and what a positive or negative result means.

Thetrauma test is a test to diagnose infection with the bacterium Helicobacter pylorii (H. pylorii). The test uses the ability of H. pyloria to secrete the enzyme urease, which breaks down urea into ammonia and carbon dioxide.

The indications for a urease test are suspected H. pyloria infection and gastric or duodenal ulcer disease.

Rapid urease test

The rapid urease test is invasive as it requires gastroscopy and the collection of a section of the gastric mucosa. Another name for this test is CLO-test (Campylobacter-like organism test). This test is used both in the diagnosis of an active bacterial infection and in assessing the effectiveness of the treatment. The advantage of the rapid urease test is that it is cheap and fast (the result is up to 15 minutes).

Breathing Trauma Test

The urea breath test is a non-invasive test. It is considered the so-called gold diagnostic standard. It is performed when the examination should be performed quickly, the patient has contraindications to gastroscopy or does not consent to it. The test is used both in the diagnosis of active bacterial infection and in the assessment of treatment effectiveness. The advantage of the urease breath test is its high sensitivity and specificity.

Urease test - what is it?

The rapid urease test involves placing a section (biopsy) of the gastric mucosa after gastroscopy on a plate containing urea with the addition of a dye (e.g. phenyl red). The decomposition of urea into ammonia and carbon dioxide by bacterial urease raises the pH of the medium (alkalinizes it) and causes the color to change from yellow to red. The biopsy should be taken from the pre-antral area as H. pyloria are usually found in this area of ​​the stomach.

  • Endoscopy: when is endoscopic examination done?

The test result is obtained after about 15 minutes, however inDepending on the manufacturer of the test, the reading time may be between 5 and 60 minutes. The sensitivity and specificity of the rapid urease test is 95% using two sections of the gastric mucosa.

  • Histopathological examination - what is it? The course and results of the histopathological examination

The respiratory urease test involves the patient swallowing a capsule with urea labeled with non-radioactive carbon13C or radioactive carbon14C (less commonly used) . In the stomach of H. pylorii, with the participation of urease, it breaks down labeled urea, and the released carbon dioxide (with labeled carbon) is excreted from the body through the lungs.

After 15-30 minutes, the content of labeled carbon in carbon dioxide in the exhaled air is determined. Carbon dioxide is determined using a scintillation counter ( 14C) or mass spectrometry ( 13C). The sensitivity of the urease respiratory test is 90-95%, and the specificity is 90-98%. It is useful in assessing the effectiveness of eradication (elimination) of H. pyloria 4 weeks after the end of therapy.

When using radioactive carbon14C, the test cannot be performed on children and pregnant women. This test is not used often due to its expensive cost and complexity.

Urease test - positive or negative

In the rapid urease test, the change in the color of the medium from yellow to red indicates the presence of H. pyloria in the tested sample.

In the urease respiratory test, the presence of carbon dioxide with labeled carbon means active infection with H. pyloria. The amount of labeled carbon dioxide in the exhaled exhalation correlates positively with the amount of H. pyloria bacteria in the gastric mucosa.

  • Helicobacter pylori - research. H. pylori detection tests
  • Helicobacter pylori - blood test. What is it?
  • Helicobacter pylori - treatment. How do I get rid of H. pylori bacteria from the body?
Worth knowing

Urease test - what influences the result?

As with all tests, the urease test can also be false negative or false positive.

A false-negative result may be due to active or recent gastric bleeding. Medications may also cause false-negative results, so 14 days before the test, you should stop taking proton pump inhibitors (PPIs), H2 receptor blockers, antibiotics, and bismuth s alts.

False positive results are very rare and may be due to infection with other bacteria, e.g. Klebsiella orProteus. This is because they can also break down urea with urease.

References

  1. Laboratory diagnostics with elements of clinical biochemistry, a textbook for medical students edited by Dembińska-Kieć A. and Naskalski J.W., Elsevier Urban & Partner Wydawnictwo Wrocław 2009, 3rd edition
  2. Internal diseases, edited by Szczeklik A., Medycyna Praktyczna Kraków 2010
  3. Bartnik W et al. Guidelines of the Polish Society of Gastroenterology concerning the diagnosis and treatment of Helicobacter pylori infection. Med Prakt 2014; 5: 46-60.
About the authorKarolina Karabin, MD, PhD, molecular biologist, laboratory diagnostician, Cambridge Diagnostics Polska A biologist by profession, specializing in microbiology, and a laboratory diagnostician with over 10 years of experience in laboratory work. A graduate of the College of Molecular Medicine and a member of the Polish Society of Human Genetics. Head of research grants at the Laboratory of Molecular Diagnostics at the Department of Hematology, Oncology and Internal Diseases of the Medical University of Warsaw. She defended the title of doctor of medical sciences in the field of medical biology at the 1st Faculty of Medicine of the Medical University of Warsaw. Author of many scientific and popular science works in the field of laboratory diagnostics, molecular biology and nutrition. On a daily basis, as a specialist in the field of laboratory diagnostics, he runs the content department at Cambridge Diagnostics Polska and cooperates with a team of nutritionists at the CD Dietary Clinic. He shares his practical knowledge on diagnostics and diet therapy of diseases with specialists at conferences, training sessions, and in magazines and websites. She is particularly interested in the influence of modern lifestyle on molecular processes in the body.

Category:

Research