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Test Code CA19_9 Carbohydrate Antigen (CA 19-9) (GI Monitor Cancer Antigen 19-9)

Important Note

Human anti-mouse antibodies (HAMA) may be present in samples from patients who have received immunotherapy utilizing monoclonal antibodies. Additionally, other heterophile antibodies such as human anti-goat antibodies may be present in patient samples.

Manufacturers formulate assays to minimize the effects of these antibodies, however careful evaluation of patient results must be done when patients are known to have such antibodies.

Access GI Monitor: potential of falsely decreased results when biotin concentrations are > 25 ng/mL.

Additional Codes

ALAB: CA19_9

Powerchart: CA 19-9

MA Cerner: CA 19-9

Specimen Requirement

Serum and heparin plasma: 0.5 mL; gel tubes are acceptable.

Additional Specimen Collection Information

  • Minimum volume: 0.5 mL serum
  • Hemolysis: Not acceptable
  • Lipemia: Specimens with ≥2+ lipemia should be cleared prior to analysis.
  • Icterus: No significant interference
  • Storage: Specimens may be stored at room temperature up to 8 hours; if longer than 8 hours refrigerate up to 48 hours; if longer than 48 hours freeze at -20 C or colder.

Reference Value

<35 U/mL

Useful For

The CA 19-9 antigen, a Lewis blood group-related mucin, is a tumor-associated antigen synthesized by normal human pancreatic and biliary ductular cells and gastric, colonic, endometrial and salivary epithelia. Typically, only a minimal amount of the CA 19-9 antigen is present in the blood of normal subjects or subjects with benign disorders. Most patients with carcinoma of the pancreas have elevated levels of blood CA 19-9 antigen.

The CA 19-9 antigen has also been identified in patients with pancreatic, bile duct, hepatocellular, stomach, colorectal, and esophageal cancers. Non-cancerous conditions that may elevate CA 19-9 antigen levels include cirrhosis, cholangitis, hepatitis, pancreatitis, and non-malignant gastrointestinal diseases.

CA 19-9 antigen levels may be used as an aid in monitoring the response to therapy for patients with pancreatic cancer.


Testing is performed Monday through Sunday.

Routine: Typically completed within 4 hours after the specimen arrives at the testing site.

CPT Code Information


Test Method

Beckman Chemiluminescent immunoassay