This kit is used for quantitative determination of pepsinogen Ⅱ (PG Ⅱ) in human serum, plasma or whole blood in vitro. Pepsinogen (PG) is a precursor of pepsin secreted by the stomach and involved in digestion. It is a single chain polypeptide with molecular weight of 42 kDa. Most of the PG is secreted into the gastric cavity, and a small part of PG can enter the blood circulation through the gastric mucosa, which is converted into active pepsin in the stomach, hydrolyzing protein and polypeptide. PG has seven isozymes, which are divided into two subgroups: PG Ⅰ and PG Ⅱ, which can be detected in blood. PG Ⅱ is composed of two isoenzymes, which are secreted not only by the main cells and mucocervical cells in the gastric fundus, but also by the pyloric gland, cardia gland and Brunner gland in the upper duodenum. Serum pepsinogen can accurately show the state and function of gastric mucosa.