What does Carbohydrate Antigen 199 (CA 199) mean?

Carbohydrate Antigen 199, also known as CA19-9, is a tumor marker primarily secreted by epithelial cells of the human pancreas, bile ducts, stomach, or colon. It exists in the serum in the form of sialylated mucin, with a normal reference range of 0-40 kU/L (the exact reference range may vary depending on the testing laboratory and conditions used). CA19-9 demonstrates the highest sensitivity for pancreatic cancer, and its levels are significantly elevated in patients with this disease, making it an important indicator for diagnosis, treatment monitoring, and detection of recurrence. In addition, elevated CA19-9 levels can also be observed, albeit to a lesser extent, in other gastrointestinal cancers such as hepatocellular carcinoma, gastric cancer, and colorectal cancer. It is important to note that an elevated CA19-9 level does not necessarily indicate cancer, as certain non-malignant conditions, such as pancreatitis and cholecystitis, may also cause an increase. Therefore, clinical evaluation should always be considered in conjunction with CA19-9 results when making a diagnosis.