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.
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.