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Urea Breath Test
(UBT)

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Medical Author:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is the urea breath test?

The urea breath test (UBT) is a test for diagnosing the presence of a bacterium, Helicobacter pylori (H. pylori) in the stomach. H. pylori causes inflammation, ulcers, and atrophy of the stomach. The test also may be used to demonstrate that H. pylori has been eliminated by treatment with antibiotics.

What is the basis of this test?

The urea breath test is based on the ability of H. pylori to break down urea, a chemical made up of nitrogen and carbon, into carbon dioxide which then is absorbed from the stomach and eliminated in the breath. (Urea normally is produced by the body from excess or "waste" nitrogen-containing chemicals and then eliminated in the urine.)

How is this breath test done?

For the test, patients swallow a capsule containing urea made from an isotope of carbon. (Isotopes of carbon occur in minuscule amounts in nature, and can be measured with special testing machines.) If H. pylori is present in the stomach, the urea is broken up and turned into carbon dioxide. The carbon dioxide is absorbed across the lining of the stomach and into the blood. It then travels in the blood to the lungs where it is excreted in the breath. Samples of exhaled breath are collected, and the isotopic carbon in the exhaled carbon dioxide is measured.

How are the results of the urea breath test interpreted?

If the isotope is detected in the breath, it means that H. pylori is present in the stomach. If the isotope is not found, H. pylori is not present. When the H. pylori is effectively treated (eradicated) by antibiotics, the test changes from positive (isotope present) to negative (isotope absent).

Are there any risks or complications of the urea breath test?

There are no risks or complications of the urea breath test.