CA19-9 Human

CA 19-9 is a type of protein known as a tetrasaccharide, specifically sialyl-LewisA. It is usually attached to O-glycans on the surface of cells and plays a role in cell-to-cell recognition processes . This protein can be found in the blood when it is shed by cancer cells .

CA 19-9 is most commonly associated with pancreatic ductal adenocarcinoma (PDAC), a highly aggressive form of pancreatic cancer that accounts for more than 80% of pancreatic cancer cases . However, elevated levels of CA 19-9 can also be found in other types of cancers, including those of the stomach, bile duct, and colon .

The CA 19-9 blood test is used primarily to monitor the progression of pancreatic cancer and to assess the effectiveness of treatment . It is not specific enough to be used as a standalone diagnostic tool because elevated levels can also be caused by benign conditions such as gallstones, pancreatitis, cystic fibrosis, and liver disease .

To perform the CA 19-9 test, a small sample of blood is collected from a vein in the patient’s arm. This sample is then analyzed in a laboratory to measure the levels of CA 19-9 . The normal range for CA 19-9 in the blood is between 0 and 37 units per milliliter (U/mL). Levels above 37 U/mL are generally considered elevated and warrant further testing .

While CA 19-9 is a useful marker for monitoring pancreatic cancer, it is not recommended as a screening test for people without symptoms of pancreatic cancer due to its lack of specificity . Additionally, different laboratories may use different methods to measure CA 19-9 levels, so it is important for patients to have follow-up tests conducted in the same lab to ensure consistency in results .