Chronic gastritis introduction, the cause of chronic gastritis, C13 website provides a detailed introduction. Chronic gastritis refers to various chronic inflammatory lesions of the gastric mucosa caused by different etiologies, and is a common chronic disease. Chronic gastritis often has a certain degree of atrophy (loss of function of the mucosa) and metaplasia, which leads to the reduction of gastric acid, pepsin, and intrinsic factor.