Carbon 13 breath test to detect H. pylori DOB value = 2 is normal and suggests no H. pylori infection. The carbon 13 breath test is one of the main methods of detecting H. pylori infection. H. pylori can produce urease, which breaks down urea. During the carbon 13 breath test, H. pylori can produce carbon 13-labeled carbon dioxide in the body, which is absorbed in the gastrointestinal tract and then reaches the lungs through the blood circulation, and then is expelled through the expiration of breath, which is used to prove the presence or absence of H. pylori infection by detecting the presence or absence of carbon 13 in the expiration of breath of the patient. DOB value is an important indicator for detecting H. pylori infection in carbon 13 breath test, which reflects the density of H. pylori in the stomach, and the higher the value, the higher the number or activity of the bacteria in the intestine. Carbon 13 breath test DOB value <4 is normal, suggesting that there is no H. pylori infection in the body, if DOB value >4, it suggests that there may be H. pylori infection, so DOB value = 2 is normal. If the DOB value is >4, you should consult a doctor for timely treatment under the doctor’s guidance, and regularly review and observe the effect of treatment, do not self-medication to avoid adverse consequences.