Pepsinogen is a precursor for the synthesis of pepsin, which is usually formed after the action of gastric acid, or other already formed and active pepsin, in the lumen of the stomach, followed by the formation of new active pepsin.
Pepsinogen is divided into pepsinogen I and pepsinogen II, with pepsinogen II, which is more associated with fundic mucosal lesions. The pepsinogen I, on the other hand, is more associated with lesions in the mucosa of the gastric sinus. Abnormalities in the values of both and changes in their ratios indicate lesions in the stomach, but not necessarily gastric cancer, and many benign lesions may also have abnormal ratios.
Elevated pepsinogen I is associated with pathological fundic gland atrophy, intestinal epithelial metaplasia, or pyloric gland metaplasia, or even atypical hyperplasia.
However, it is not just one indicator, but also a combination of symptoms and a combination of pepsinogen I and pepsinogen I to pepsin II ratio to determine whether there is a lesion in the stomach, and a progressive decrease in the ratio is associated with progressive gastric mucosal atrophy, so gastroscopy and H. pylori are indicated.