Carbohydrate Antigen 19-9 (CA 19-9), Serum analysis is a laboratory test mainly used as a biomarker to monitor certain types of cancer, especially pancreatic cancer. CA 19-9 is a protein produced in higher amounts in tumor conditions, making it a useful tool for assessing the presence of disease and monitoring response to treatment. This test is usually performed by taking a blood sample to measure CA 19-9 levels. Elevated levels may indicate the presence of cancer or other medical conditions such as pancreatitis or bile duct obstruction. This analysis helps physicians make informed decisions regarding disease diagnosis and follow-up, contributing to improved treatment plans and patient care.