What does an H. pylori urea breath test look for?

The H. pylori urea breath test detects the presence of H. pylori, a bacteria that causes ulcers in the duodenum and stomach. The test measures the amount of exhaled carbon dioxide in the breath of the patient after swallowing a tablet containing the chemical 'urea,' according to WebMD.

The urease enzyme found within the bacteria breaks down urea in the tablet into ammonia and carbon dioxide, according to WebMD. Once the tablet is swallowed, the concentration of carbon dioxide in the breath is measured and compared to a pre-tablet sample. High amounts of carbon dioxide typically indicate that H. pylori is present within the digestive system.