PGI is the abbreviation of Pepsinogen 1, and a low level suggests a decrease in gastric acid secretion or atrophy of the gastric mucosal glands. The causes of low pepsinogen include dietary causes, medication causes and disease causes. 1. Lifestyle and dietary reasons: such as drinking alcohol, eating stimulating food, etc. will inhibit the secretion of pepsinogen 1, generally can be restored after adjusting lifestyle and diet. 2. Drug causes: such as long-term use of aspirin, proton pump inhibitors (such as rabeprazole, pantoprazole), hormones (such as methylprednisolone, dexamethasone) and other drugs, can inhibit pepsinogen 1 secretion. 3. Disease causes: such as Helicobacter pylori infection, atrophic gastritis, peptic ulcer, gastric tumors and so on. These diseases can cause damage to the gastric mucosa, resulting in decreased secretion of pepsinogen 1. If there is a decrease in pepsinogen 1, it is recommended to consult a doctor to analyze the specific causes in conjunction with the condition.