The urea breath test (UBT) is a test for diagnosing the presence of a bacterium, Helicobacter pylori (H. pylori) in the stomach which causes inflammation, ulcers, and atrophy of the stomach, and to demonstrate that bacteria has been eliminated by treatment with antibiotics.
During the test, the patient swallows a capsule containing urea made from an isotope of carbon. Normally, urea is produced by the body from excess or "waste" nitrogen-containing chemicals and then eliminated in the urine.
If H. pylori are present in the stomach, the urea is broken up and turned into carbon dioxide which is absorbed across the lining of the stomach and into the blood.
From blood, it travels 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.
The test is positive and H. pylori are present if the isotope is detected in the breath. It can be effectively treated (eradicated) by antibiotics.
After a therapy test can be repeated and if it was effective, the test will change from positive to negative. There are no risks or complications of the urea breath test.