Urea Breath Test (UBT)

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) infection 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 preparation for the urea breath test? How is it performed?

Your doctor or other health care professional will provide you with instructions to prepare for the urea breath test.

During the test you will swallow a capsule containing urea, which is 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 does the urea breath test diagnose H. pylori infection?

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.)

H. pylori

Helicobacter pylori (H. pylori or, as it is sometimes termed, stomach bacteria) is a spiral-shaped gram-negative bacterium that can cause chronic inflammation of the inner lining of the stomach (gastritis) and in the duodenum (first part of the small bowel) in humans. This bacterium also is considered a common cause of ulcers worldwide; as many as 90% of people with ulcers are infected with H. pylori. However, many people have these organisms residing in (colonising or mucosa-associated) their stomach and upper digestive tract and have few or no symptoms. LPS (lipopolysaccharide) is part of the H. pylori outer membrane and can be toxic when the bacteria die and lyse.

How are the results of the urea breath test interpreted?

If the urea breath test is positive and the isotope is detected in the breath, it means that H. pylori is present in the stomach. If the isotope is not found in the breath, the test results are negative for the infection.

When the H. pylori is effectively treated (eradicated) by antibiotics, the test changes from positive (isotope present) to negative (isotope absent).

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

There are no side effects, risks, or complications of the urea breath test. You do not need to stop taking medications, including proton pump inhibitors (PPIs), prior to having the procedure performed by a doctor.


Bowel regularity means a bowel movement every day. See Answer

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Crowe, Sheila E. "Indications and diagnostic tests for Helicobacter pylori infection." UptoDate.com. June 2018.