The correct name for the carbon 14 test should be the carbon 14 urea breath test. The carbon 14 urea breath test requires fasting. Carbon 14 Urea Breath Test is designed to determine whether a patient has H. pylori infection. The principle is that H. pylori can produce highly active urease, and when a patient takes carbon 14 labeled urea, if the patient has H. pylori infection, it will produce urease that breaks down the urea into ammonia and carbon 14 labeled carbon dioxide, so the patient’s exhaled breath is collected and analyzed for the amount of carbon 14 labeled carbon dioxide in the breath. content in the gas to determine whether the patient has H. pylori infection. If the patient has not fasted, the carbon 14-labeled urea taken is difficult to come into contact with H. pylori on the gastric mucosa, which may result in a false negative. If you suspect that you have H. pylori infection, you should go to the hospital in time and improve the relevant examination under the guidance of the doctor to clarify the diagnosis and treatment.