The Pepsinogens are gastric acid protease zymogens. They are divided into two distinct immunochemical groups. Pepsinogen I and II. Pepsinogen II is one of 4 aspartic proteinases: PG I, PG II, Cathepsin E and D. Pepsinogen II is produced primarily in the Oxyntic gland mucosa of the stomach, the gastric antrum and the duodenum. It is secreted mainly into the gastric lumen and into circulation. Pepsinogen II has little or no biological activity but in acid is converted to the active enzyme Pepsin which exhibits proteolytic actions. Unlike Pepsinogen I, Pepsinogen II is not normally found in the urine. Patients with pernicious anemia have low to non-detectable levels of Pepsinogen I but normal levels of Pepsinogen II. Pepsinogen II levels are slightly elevated in gastric ulcer. Patients with Zollinger-Ellison's syndrome exhibit greatly elevated levels.