The principle of 13C breath test is to introduce a substrate labeled with the stable nucleophile 13C into the body (mainly by oral administration), and use isotope ratio mass spectrometry to detect changes in the final metabolite of the substrate, 13CO2, to study metabolic reactions and physiological processes in the body. 13C breath test is widely used in the examination of digestive system diseases. Gastric H. pylori test: Diagnosis can be obtained in 2 minutes with just one breath. It is especially suitable for review after H. pylori eradication treatment because it is painless without gastroscopy, and is widely used at home and abroad. Gastric emptying function: It is used to diagnose delayed gastric emptying caused by various reasons, especially for the diagnosis and efficacy observation of diabetic gastroparesis. Its accuracy is comparable to that of scintigraphy, and non-invasive and non-radioactive, which is significantly better than scintigraphy. Exocrine pancreatic function testing: Exocrine pancreatic function testing has always been a clinical and scientific problem, and the existing testing methods are complicated, painful to patients and difficult to popularize. 3C breath test has emerged to provide a new way to diagnose pancreatic diseases. Its advantages are immediacy, non-invasive, non-radioactive and early diagnosis. Hepatocyte function test: Compared with traditional liver function test, it has the advantages of immediacy, non-invasive, convenience and early diagnosis. The outstanding advantage is its immediacy, reflecting the latest liver function, whereas traditional liver function tests reflect the average level of liver function over a period of time. 13C breath test can also be used for the detection of lactose deficiency and small intestine bacterial overgrowth: The 13C infrared energy spectrum analyzer introduced by our department is the first of its kind in Tianjin, and is characterized by immediacy, non-invasiveness, non-radiation and early diagnosis. It is suitable for the diagnosis and efficacy observation of many diseases, especially for H. pylori detection and pancreatic exocrine function detection, which have the advantages that cannot be replaced by other methods.