Inflammation of the duodenum can mildly increase CA199, but it is generally considered to be of no diagnostic significance. CA199 is a tumor marker that can be used as a diagnostic reference for pancreatic cancer, cholangiocarcinoma and other tumors, with a normal range of 0kU/L to 40kU/L. However, it usually has clinical diagnostic significance only when it is significantly elevated. When duodenal inflammation occurs, some patients may have a mild increase in serum CA199, which is generally considered to be of no clinical significance, not related to tumors, and cannot be used for the diagnosis of duodenal inflammation. If you need to clarify your condition, you should go to the hospital for a complete barium meal, gastroscopy and other related examinations. It should be noted that if there is a significant increase in serum CA199 in duodenal inflammation, it is necessary to be alert to the presence of undetected gastrointestinal tumors, and the results of the examination should be reported to the physician for evaluation as soon as possible.